parallel lines lines that intersect are in a common plane. euclid's fifth postulate 18 lines that...

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  • 1

  • 2

    GeometryParallelLines

    20161115

    www.njctl.org

    http://www.njctl.org

  • 3

    TableofContentsClickonthetopictogotothatsection

    Lines:Intersecting,Parallel&Skew

    ConstructingParallelLines

    Lines&Transversals

    ParallelLines&Proofs

    PropertiesofParallelLines

    PARCCSampleQuestions

  • 4

    ConstructionsVideosTableofContentsClickonthetopictogotothatvideo

    ParallelLinesCorrespondingAngles

    ParallelLinesAlternateInteriorAngles

    ParallelLinesAlternateExteriorAngles

    ParallelLinesusingMenuOptions

  • 5

    Throughoutthisunit,theStandardsforMathematicalPracticeareused.

    MP1:Makingsenseofproblems&persevereinsolvingthem.MP2:Reasonabstractly&quantitatively.MP3:Constructviableargumentsandcritiquethereasoningofothers.MP4:Modelwithmathematics.MP5:Useappropriatetoolsstrategically.MP6:Attendtoprecision.MP7:Lookfor&makeuseofstructure.MP8:Lookfor&expressregularityinrepeatedreasoning.

    Additionalquestionsareincludedontheslidesusingthe"MathPractice"Pulltabs(e.g.ablankoneisshowntotherightonthisslide)withareferencetothestandardsused.

    Ifquestionsalreadyexistonaslide,thenthespecificMPsthatthequestionsaddressarelistedinthePulltab.

    MathPractic

    e

  • 6

    Lines:Intersecting,Parallel&Skew

    ReturntoTableofContents

  • 7

    Euclid'sFifthPostulate

    Euclid'sFifthPostulateisperhapshismostfamous.

    It'sbotheredmathematiciansforthousandsofyears.

    FifthPostulate:That,ifastraightlinefallingontwostraightlinesmaketheinterioranglesonthesamesidelessthantworightangles,thetwostraightlines,ifproducedindefinitely,meetonthatsideonwhicharetheangleslessthanthetwo

    rightangles.

  • 8

    Euclid'sFifthPostulate

    ThisseemedsonaturalthattheGreekgeometersthoughttheyshouldbeabletoproveit,andwouldn'tneedittobeapostulate.

    Theyresistedusingitforyears.

    However,theyfoundthattheyneededit.

    Andtheycouldn'tproveit.

    Theyjusthadtopostulateit.

  • 9

    Itsaysthattherearetwopossiblecasesifonelinecrossestwoothers.

    Euclid'sFifthPostulate

    1 2

    3 4

  • 10

    Thepairsofanglesonbothsides,(either1&3or2&4)eachaddupto180,tworightangles,andthetworedlinesnevermeet.

    Likethis....

    Euclid'sFifthPostulate

    1 2

    3 4

  • 11

    Orlikethis.

    1 2

    3 4

    Euclid'sFifthPostulate

    Or,...

  • 12

    Theyadduptolessthan180ononeside(angles2&4),andmorethan180ontheother(angles1&3),inwhichcasethelinesmeetonthesidewiththesmallerangles.

    Likethis...

    1 2

    3 4

    Euclid'sFifthPostulate

  • 13

    Orlikethis.

    Euclid'sFifthPostulate

    1 2

    3 4

  • 14

    Theycouldn'tprovethisfromtheotheraxiomsandpostulates.But,withoutittherewerealotofimportantpiecesofgeometrythey

    couldn'tprove.

    SotheygaveinandmadeitthefinalpostulateofEuclideanGeometry.Forthenextthousandsofyears,mathematiciansfeltthesameway.Theykepttryingtoshowwhythispostulatewasnot

    needed.

    Noonesucceeded.

    Euclid'sFifthPostulate

  • 15

    In1866,BernhardRiemanntooktheotherperspective.

    ForhisdoctoraldissertationhedesignedageometryinwhichEuclid'sFifthPostulatewasnottrue,ratherthanassumingitwas.

    ThisledtononEuclideangeometry.Whereparallellinesalwaysmeet,ratherthannevermeet.

    Euclid'sFifthPostulate

  • 16

    Buthalfacenturylater,nonEuclideangeometry,basedonrejectingthefifthpostulate,becamethemathematicalbasisofEinstein'sGeneralRelativity.

    Itcreatestheideaofcurvedspacetime.Thisisnowtheacceptedtheoryfortheshapeofouruniverse.

    Euclid'sFifthPostulate

  • 17

    Linesthatareinthesameplaneandnevermeetarecalledparallel.

    Linesthatintersectarecallednonparallelorintersecting.Alllinesthatintersectareinacommonplane.

    Euclid'sFifthPostulate

  • 18

    Linesthatareindifferentplanesandnevermeetarecalledskew.

    Euclid'sFifthPostulate

    m

    n

    P

    Q

    Linesm&ninthefigureareskew.

  • 19

    B

    a

    TheParallelPostulate

    OnewayofrestatingEuclid'sFifthPostulateistosaythatparallellinesnevermeet.

    AnextensionofitistheParallelPostulate:givenalineandapoint,notontheline,thereisone,andonlyone,linethatcanbedrawnthroughthepointwhichisparalleltotheline.

    Canyouestimatewhere

    theparallellinewouldbe?

    MathPractic

    e

    QuestiononthisslideaddressesMP2

  • 20

    B

    a

    CanyouimagineanyotherlinewhichcouldbedrawnthroughPointBandstillbeparalleltolinea?

    TheParallelPostulate

    MathPractic

    e

    QuestiononthisslideaddressesMP2

  • 21

    Parallellinesaretwolinesinaplanethatnevermeet.

    WewouldsaythatlinesDEandFGareparallel.

    Or,symbolically:

    Parallel,IntersectingandSkew

    DE FG

    D E

    F G

    MathPractic

    e

  • 22

    Linescannotbeassumedtobeparallelunlessitisindicatedthattheyare.Justlookingliketheyareparallelisnotsufficient.

    Therearetwowaysofindicatingthatlinesareparallel.

    Thefirstwayisasshownonthepriorslide:

    IndicatingLinesareParallel

    D E

    F G

    DE FG

  • 23

    IndicatingLinesareParallel

    m

    k

    Theotherwaytoindicatelinesareparallelistolabelthemwitharrows,asshownbelow.

    Thelineswhichsharethearrow(showninredtomakeitmorevisiblehere)areparallel.

    Iftwodifferentpairsoflinesareparallel,theoneswiththematchingnumberofarrowsareparallel,asshownonthenextslide.

    MathPractic

    e

  • 24

    IndicatingLinesareParallel

    m

    k

    a

    b

    Thisindicatesthatlineskandmareparalleltoeachother.

    And,linesaandbareparalleltoeachother.

    Butlineskandmarenotparalleltoaandb.

  • 25

    Iftwodifferentlinesinthesameplanearenotparalleltheyareintersecting,andtheyintersectatonepoint.

    Wealsoknowthatfouranglesareformed.

    Parallel,IntersectingandSkew

    D

    E

    F G

  • 26

    Fromthesefourangles,therearefourpairsoflinearanglesthatareformedorlinearpairs.

    Linearpairsareadjacentanglesformedbyintersectinglinestheanglesaresupplementary.

    1&3areonelinearpair

    Parallel,IntersectingandSkew

    D

    E

    F G1 2

    3 4

    Listtheotherlinearpairs.

    Ans

    wer

  • 27

    Iftheadjacentanglesformedbyintersectinglinesarecongruent,thelinesareperpendicular.

    PerpendicularLines

    D

    E

    F G

    DE FGSymbolically,thisisstatedas

    MathPractic

    e

  • 28

    Iftwolinesintersect,thentheydefineaplane,soarecoplanar.

    SkewLines

    m

    n Q

    PLinesm&ninthefigureareskew.

    Twolinesthatdonotintersectcaneitherbeparalleliftheyareinthesameplaneorskewiftheyareindifferentplanes.

    MathPractic

    e

  • 29

    Usingthefollowingdiagram,namealinewhichisskewwithLineHG:alinethatdoesnotlieinacommonplane.

    A B

    CD

    E F

    GH

    SkewLines

    Ans

    wer

    ThisexampleaddressesMP2

  • 30

    1 Arelinesaandbskew?

    Yes No

    a

    b

    G Ans

    wer Yes,linesaandbareskew.Linesaandbare

    noncoplanaranddonotintersect.

  • 31

    2 HowmanylinescanbedrawnthroughCandparalleltoLineAB?

    B

    AC

    Ans

    wer

  • 32

    A B

    CD

    E F

    GH

    3 NamealllinesparalleltoEF.

    A ABB BCC DCD HDE HG

    Ans

    wer

  • 33

    4 NamelinesskewtoEF.

    A BCB DCC HDD ABE GC

    A B

    CD

    E F

    GH

    Ans

    wer

  • 34

    5 Twointersectinglinesarealwayscoplanar.

    True False

    Ans

    wer

  • 35

    6 Twoskewlinesarecoplanar.

    True False

    Ans

    wer

  • 36

    7 Completethisstatementwiththebestappropriateword:

    Twoskewlinesare__________parallel.

    A alwaysB neverC sometimes

    Ans

    wer

  • 37

    Lines&Transversals

    ReturntoTableofContents

  • 38

    123 4

    56

    7 8

    k

    m

    n

    Transversals

    (ThisisthenameofthelinethatEuclidusedtointersecttwolinesinhisfifthpostulate.)

    Intheimage,transversal,Linen,isshownintersectingLinekandLinem.

    ATransversalisalinethatintersectstwoormorecoplanarlines.

    LinekandLinemmayormaynotbeparallel.

  • 39

    InteriorAnglesarethe4anglesthatliebetweenthetwolines.

    Whenatransversalintersectstwolines,eightanglesareformed.Theseanglesaregivenspecialnames.

    3 4

    56

    k

    m

    n

    AnglesFormedbyaTransversal

  • 40

    ExteriorAnglesarethe4anglesthatlieoutsidethetwolines.

    Whenatransversalintersectstwolines,eightanglesareformed.Theseanglesaregivenspecialnames.

    12

    7 8

    k

    m

    n

    AnglesFormedbyaTransversal

  • 41

    8 Namealloftheinteriorangles.

    A 1

    B 2

    C 3

    D 4

    E 5

    F 6

    G 7

    H 8

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 42

    9 Namealloftheexteriorangles.

    A 1

    B 2

    C 3

    D 4

    E 5

    F 6

    G 7

    H 8

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 43

    CorrespondingAnglesarepairsofanglesthatlieinthesamepositionrelativetothetransversal,asshownabove.

    CorrespondingAngles

    123 4

    567 8

    k

    n

    m

    Therearefourpairsofcorrespondinganglesformedwhenatransversalintersectstwolines.

  • 44

    10 Whichanglecorrespondswith1?

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 45

    11 Whichanglecorrespondswith7?

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 46

    12 Whichanglecorrespondswith6?

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 47

    13 Whichanglecorrespondswith4?

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 48

    Therearetwopairsformedbythetransversaltheyareshownaboveinredandblue.

    AlternateInteriorAngles

    3 4

    56

    k

    m

    n

    AlternateInteriorAnglesareinterioranglesthatlieonoppositesidesofthetransversal.

    MathPractic

    e

    MP6Emphasizebreakingapartthewordsineachvocabularytermtounderstandthemeaning.

    Alternatemeans"opposite"Interiormeans"inside"

    SoAlternateInteriorAnglesareonoppositesidesofthetransversalandinsideoftheother2lines.

  • 49

    AlternateExteriorAngles

    12

    7 8

    k

    m

    n

    Therearetwopairsformedbythetransversaltheyareshownaboveinredandblue.

    AlternateExteriorAnglesareexterioranglesthatlieonoppositesidesofthetransversal.

    MathPractic

    e

    MP6Emphasizebreakingapartthewordsineachvocabularytermtounderstandthemeaning.

    Alternatemeans"opposite"Exteriormeans"outside"

    SoAlternateExteriorAnglesareonoppositesidesofthetransversalandoutsideoftheother2lines.

  • 50

    14 Whichisthealternateinterioranglethatispairedwith3?

    A 1B 2C 3D 4

    E 5F 6G 7H 8

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 51

    15 Whichisthealternateexterioranglethatispairedwith7?

    123 4

    567 8

    k

    m

    nA 1B 2C 3D 4E 5F 6G 7H 8

    Ans

    wer

  • 52

    123 4

    567 8

    k

    m

    n

    16 Whichisthealternateexterioranglethatispairedwith2?

    A 1B 2C 3D 4E 5F 6G 7H 8

    Ans

    wer

  • 53

    123 4

    567 8

    k

    m

    n

    17 Whichisthealternateinterioranglethatispairedwith6?

    A 1B 2C 3D 4E 5F 6G 7H 8

    Ans

    wer

    D

  • 54

    SameSideInteriorAngles

    Therearetwopairsformedbythetransversaltheyareshownaboveinredandblue.

    3 4

    56

    k

    m

    n

    SameSideInteriorAnglesareinterioranglesthatlieonthesamesideofthetransversal.

    MathPractic

    e

    MP6Emphasizebreakingapartthewordsineachvocabularytermtounderstandthemeaning.

    Samesidemeans"onthesameside",Interiormeans"inside"SoSameSideInteriorAngles

    areonsamesideofthetransversalandinsideoftheother2lines.Note:a.k.a.

    ConsecutiveInteriorAngles

  • 55

    SameSideExteriorAngles

    Therearetwopairsformedbythetransversaltheyareshownaboveinredandblue.

    12

    7 8

    k

    m

    n

    SameSideExteriorAnglesareexterioranglesthatlieonthesamesideofthetransversal.

    MathPractic

    e

  • 56

    123 4

    567 8

    k

    m

    n

    18 Whichisthesamesideinterioranglethatispairedwith6?

    A 1B 2C 3D 4E 6F 7G 8

    Ans

    wer

    C

  • 57

    123 4

    567 8

    k

    m

    n

    19 Whichisthesamesideexterioranglethatispairedwith7?

    A 1B 2C 3D 4E 6F 7G 8

    Ans

    wer

    B

  • 58

    123 4

    567 8

    k

    m

    n

    a.1and2

    b.1and3

    c.1and5

    d.3and6

    e.3and5

    f.2and8

    Slideeachwordintotheappropriatesquaretoclassifyeachpairofangles.

    ClassifyingAngles

    AlternateExteriorSameSideInteriorVertical

    CorrespondingSameSideExterior AlternateInteriorLinearPair

    Ans

    wer

  • 59

    1 23 4

    5 67 8

    kj

    t

    20 3and6are...

    A CorrespondingAnglesB AlternateExteriorAnglesC SameSideExteriorAnglesD VerticalAnglesE Noneofthese

    Ans

    wer

    B

  • 60

    1 23 4

    5 67 8

    kj

    t

    21 1and6are____.

    A CorrespondingAnglesB AlternateExteriorAnglesC SameSideExteriorAnglesD VerticalAnglesE Noneofthese

    Ans

    wer

    C

  • 61

    1 23 4

    5 67 8

    kj

    t

    22 2and7are____.

    A CorrespondingAnglesB AlternateInteriorAnglesC SameSideInteriorAnglesD VerticalAnglesE Noneofthese An

    swer

    B

  • 62

    1 23 4

    5 67 8

    kj

    t

    23 4and8are____.

    A CorrespondingAnglesB AlternateExteriorAnglesC SameSideExteriorAnglesD VerticalAnglesE Noneofthese

    Ans

    wer

    A

  • 63

    1 23 4

    5 67 8

    kj

    t

    24 1and7are____.A CorrespondingAnglesB AlternateExteriorAnglesC SameSideExteriorAnglesD VerticalAnglesE Noneofthese

    Ans

    wer E

    Theseangleshavenorelationshipw/oneanother

  • 64

    1 23 4

    5 67 8

    kj

    t

    25 5and8are____.

    A CorrespondingAnglesB AlternateExteriorAnglesC SameSideExteriorAnglesD VerticalAnglesE Noneofthese

    Ans

    wer

    D

  • 65

    1 23 4

    5 67 8

    kj

    t

    26 2and5are____.

    A CorrespondingAnglesB AlternateInteriorAnglesC SameSideInteriorAnglesD VerticalAnglesE Noneofthese

    Ans

    wer

    C

  • 66

    ParallelLines&Proofs

    ReturntoTableofContents

    Lab:StartingaBusinessWorksheet

    Lab:StartingaBusinessTeacherSlides

    MathPractic

    e

    ThislabaddressesMP1,MP3,MP4,MP6&MP7

    http://www.njctl.org/courses/math/geometry/parallel-lines/starting-a-business-lab-2/http://www.njctl.org/courses/math/geometry/parallel-lines/starting-a-business-lab-slides-2/

  • 67

    Inadditiontothepostulatesandtheoremsusedsofar,therearethreeessentialpropertiesofcongruenceuponwhichwe

    willrelyasweproceed.

    Therearealsofourpropertiesofequality,threeofwhicharecloselyrelatedtomatchingpropertiesofcongruence.

    PropertiesofCongruenceandEquality

  • 68

    TheyallrepresentthesortofcommonsensethatEuclidwouldhavedescribedasaCommonUnderstanding,andwhichwe

    wouldnowcallanAxiom.

    Thecongruencepropertiesaretrueforallcongruentthings:linesegments,anglesandfigures.

    Theequalitypropertiesaretrueforallmeasuresofthingsincludinglengthsoflinesandmeasuresofangles.

    PropertiesofCongruenceandEquality

  • 69

    Athingisalwayscongruenttoitself.

    Whilethisisobvious,itwillbeusedinprovingtheoremsasareason.

    Forinstance,whenalinesegmentservesasasideintwodifferenttriangles,youcanstatethatthesidesofthosetrianglesarecongruentwiththereason:

    ReflexivePropertyofCongruence

    ReflexivePropertyofCongruence

    A B

    CD

    Inthediagram,ACAC

  • 70

    Themeasuresofanglesorlengthsofsidescanbetakentobeequaltothemselves,eveniftheyarepartsof

    differentfigures,

    withthereason:

    ReflexivePropertyofEquality

    ReflexivePropertyofEquality

    A B DC

    TheLineSegmentAdditionPostulatetellusthat

    AC=AB+BCandBD=CD+BC

    TheReflexivePropertyofEqualityindicatesthatthelengthBCisequaltoitselfinbothequations

  • 71

    SymmetricPropertyofCongruence

    Ifonethingiscongruenttoanother,thesecondthingisalsocongruenttothefirst.

    Again,thisisobviousbutallowsyoutoreversetheorderofthestatementsaboutcongruentpropertieswiththereason:

    SymmetricPropertyofCongruence

    Forexample:

    ABCiscongruentto DEFthat DEFiscongruentto ABC,

  • 72

    SymmetricPropertyofEquality

    Ifonethingisequaltoanother,thesecondthingisalsoequaltothefirst.

    Again,thisisobviousbutallowsyoutoreversetheorderofthestatementsaboutequalpropertieswiththereason:

    SymmetricPropertyofEquality

    Forexample:

    Ifm ABC=m DEF,thenm DEF=m ABC,

  • 73

    Iftwothingsarecongruenttoathirdthing,thentheyarealsocongruenttoeachother.

    So,ifABCiscongruenttoDEFandLMNisalsocongruenttoDEF,thenwecansaythatABCiscongruenttoLMNduetothe

    Withthereason:

    TransitivePropertyofCongruence

    TransitivePropertyofCongruence

  • 74

    Iftwothingsareequaltoathirdthing,thentheyarealsoequaltoeachother.

    IfmA=mBandmC=mB,thenmA=mC

    Thisisidenticaltothetransitivepropertyofcongruenceexceptitdealswiththemeasureofthingsratherthanthethings.

    TransitivePropertyofEquality

    TransitivePropertyofEquality

  • 75

    Ifonethingisequaltoanother,thenonecanbesubstitutedforanother.

    Thisisacommonstepinaproofwhereonethingisprovenequaltoanotherandreplacesthatotherinanexpressionusingthereason:

    SubstitutionPropertyofEquality

    Forinstanceifx+y=12,andx=2y

    Wecansubstitute2yforxtoget

    2y+y=12

    andusethedivisionpropertytogety=4

    SubstitutionPropertyofEquality

  • 76

    123 4

    567 8

    k

    m

    n

    CorrespondingAnglesTheorem

    AccordingtotheCorrespondingAngleswhichoftheaboveanglesarecongruent?

    Ifparallellinesarecutbyatransversal,thenthecorrespondinganglesarecongruent.

    Ans

    wer

    AccordingtoCorrespondingAnglesPostulatethefollowinganglesare

    congruent:

    15263748

  • 77

    Wecouldpickanypairofcorrespondingangles:2&63&71&5or4&8.

    Together,let'sprovethat2&6arecongruent.

    CorrespondingAnglesProof

    Tokeeptheargumentclear,let'sjustproveonepairofthoseanglesequalhere.Youcanfollowthesameapproachtoprovetheotherthreepairsofanglesequal.

    123 4

    567 8

    k

    m

    n

  • 78

    Given:LinemandLinekareparallelandintersectedbylinen

    Prove:m2=m6

    CorrespondingAnglesProof

    123 4

    567 8

    k

    m

    n

  • 79

    Statement1LinemandLinekareparallelandintersectedbylinen

    Reason1Given

    CorrespondingAnglesProof

    123 4

    567 8

    k

    m

    nGiven:LinemandLinekareparallelandintersectedbylinen

    Prove:m2=m6

    MathPractic

    e

    MP7Emphasizethatthe1ststeptoanyproofisstatingthe"Givens".Then,oneusesthepropertiesofthe1st

    statementtoaskquestionsandcontinuetosolvethe

    proof.

  • 80

    FifthPostulate:That,ifastraightlinefallingontwostraightlinesmaketheinterioranglesonthesamesidelessthantworightangles,thetwostraightlines,ifproducedindefinitely,meetonthatsideofwhicharetheangleslessthanthetworightangles.

    RememberEuclid'sFifthPostulate.Theonethatnoonelikesbutwhichtheyneed.Thisiswhereit'sneeded.

    Euclid'sFifthPostulate

    CorrespondingAnglesProof

    123 4

    567 8

    k

    m

    nGiven:LinemandLinekareparallelandintersectedbylinen

    Prove:m2=m6

  • 81

    Euclid'sFifthPostulate

    1 2

    3 4

    Recallthatwelearnedearlyinthisunitthatthismeansthat...

    Ifthepairsofinterioranglesonbothsidesofthetransversal,(both1&3or2&4)eachaddupto180,thetworedlinesareparallel...andnevermeet.

  • 82

    123 4

    567 8

    k

    m

    n

    27 So,inthiscase,whichanglesmustaddupto180basedonEuclid'sFifthPostulate?

    A 1&4

    B 6&8

    C 4&5

    D 3&6

    E Alloftheabove

    Ans

    wer

    C&D

  • 83

    Reason2Euclid'sFifthPostulate

    Statement2m3+m6=180m4+m5=180

    Whenanglessumto180,whattypeofanglesarethey?

    CorrespondingAnglesProof

    123 4

    567 8

    k

    m

    n

    Given:LinemandLinekareparallelandintersectedbylinen

    Prove:m2=m6

    MathPractic

    e

    QuestionsonthisslideaddressMP2&MP3.

  • 84

    Reason3DefinitionofSupplementaryAngles

    Statement33&6aresupplementary4&5aresupplementary

    Whichotherangleissupplementaryto3,becausetogethertheyformastraightangle?Howabouttoangle6?

    CorrespondingAnglesProof

    123 4

    567 8

    k

    m

    n

    Given:LinemandLinekareparallelandintersectedbylinen

    Prove:m2=m6

    MathPractic

    e

    QuestionsonthisslideaddressMP2&MP3.

  • 85

    Reason4Anglesthatformalinearpairaresupplementary

    Statement42&3aresupplementary

    Whatdoweknowaboutangleswhohavethesamesupplements?

    CorrespondingAnglesProof

    123 4

    567 8

    k

    m

    n

    Given:LinemandLinekareparallelandintersectedbylinen

    Prove:m2=m6

    MathPractic

    e

    QuestionsonthisslideaddressMP2&MP4.

  • 86

    Reason5Twoanglessupplementarytothesameangleareequal

    Statement5m2=m6

    CorrespondingAnglesProof

    123 4

    567 8

    k

    m

    n

    Given:LinemandLinekareparallelandintersectedbylinen

    Prove:m2=m6

  • 87

    Statement Reason

    1 LinemandLinekareparallelandintersectedbyLinen Given

    2 m4+m5=180m3+m6=180

    Euclid'sFifthPostulate

    3 4&5aresupplementary3&6aresupplementaryDefinitionofsupplementaryangles

    4 3&2aresupplementary Anglesthatformalinearpairaresupplementary

    5 m2=m6Twoanglessupplementarytothesameangleareequal

    CorrespondingAnglesProofGiven:LinemandLinekareparallelandintersectedbyLinen

    Prove:m2=m6

    123 4

    567 8

    k

    m

    n

  • 88

    PropertiesofParallelLines

    Thisisanimportantresult,whichwasonlymadepossiblebyEuclid'sFifthPostulate.

    Itleadstosomeotherprettyimportantresults.Itallowsustoprovesomepairsofanglescongruentandsomeotherpairsofanglessupplementary.

    And,itworksinreverse,ifanyoftheseconditionsaremetwecanprovethatlinesareparallel.

    123 4

    567 8

    k

    m

    n

  • 89

    ConversesofParallelLineProofs

    Weprovedthatiftwolinesareparallel,theircorrespondinganglesareequal.

    Theconversemustalsobetrue:

    Iftwolinesarecutbyatransversalandthecorrespondinganglesarecongruent,thenthelinesareparallel. Te

    ache

    rNotes

    Youmightneedtoexplainthedifferencebetweenanoriginalifthenstatementanditsconverse,whichisformedbyswitchingthehypothesis&conclusion.Ex:Original:Ifitis3pminNewJersey,thenitis1pminColorado.Converse:Ifitis1pminColorado,thenitis3pminNewJersey.

  • 90

    ConversesofParallelLineProofs

    Thesamereason:CorrespondingAnglesofParallelLinesareEqualisusedineachcase.

    Toprovetherelationshipbetweencertainanglesifweknowthelinesareparallel

    OR

    Toprovethatthelinesareparallelifweknowtherelationshipbetweenthoseangles.

  • 91

    ConversesofParallelLineProofs

    Thispatternwillbetrueofeachtheoremweproveabouttheanglesformedbythetransversalintersectingtheparallellines.

    Theyprovetherelationshipbetweenanglesoflinesknowntobeparallel,ortheyprovethatthelinesareparallel.

  • 92

    123 4

    567 8

    k

    m

    n

    AlternateInteriorAnglesTheorem

    AccordingtotheAlternateInteriorAnglesTheoremwhichoftheseanglesarecongruent?

    Ifparallellinesarecutbyatransversal,thenthealternateinterioranglesarecongruent.

    Ans

    wer

  • 93

    Given:LinemandLinekareparallelandintersectedbylinen

    Prove:35and46

    AlternateInteriorAnglesProof

    123 4

    567 8

    k

    m

    n

  • 94

    Statement1LinemandLinekareparallelandintersectedbylinen

    Reason1Given

    AlternateInteriorAnglesProof

    AccordingtotheCorrespondingAnglesTheoremwhichoftheaboveanglesarecongruent?

    123 4

    567 8

    k

    m

    n

    Given:LinemandLinekareparallelandintersectedbylinen

    Prove:35and46

    MathPractic

    e

    QuestiononthisslideaddressesMP3&MP6.

  • 95

    Reason2Whentwoparallellinesarecutbyatransversal,thecorrespondinganglesarecongruent.

    Statement21526

    Whichotherangleiscongruentto1?Whichotherangleiscongruentto2?Whyaretheseanglescongruent?

    AlternateInteriorAnglesProof

    123 4

    567 8

    k

    m

    nGiven:LinemandLinekareparallelandintersectedbylinen

    Prove:35and46

    MathPractic

    e

    QuestionsonthisslideaddressMP3,MP6&MP7.

  • 96

    Reason3Verticalanglesarecongruent.

    Whatdoweknowaboutanglesthatarecongruenttothesameangle?Explainyouranswer.

    AlternateInteriorAnglesProof

    Statement31324

    123 4

    567 8

    k

    m

    n

    Given:LinemandLinekareparallelandintersectedbylinen

    Prove:35and46

    MathPractic

    e

    QuestionsonthisslideaddressMP2,MP3&MP6.

  • 97

    Reason4Transitivepropertyofcongruence

    Statement4 3 5 4 6

    Butthosearethepairsofalternateinteriorangleswhichwesetouttoprovearecongruent.So,ourproofiscomplete:AlternateInteriorAnglesofParallelLinesareCongruent

    AlternateInteriorAnglesProof

    123 4

    567 8

    k

    m

    n

    Given:LinemandLinekareparallelandintersectedbylinen

    Prove:35and46

  • 98

    Statement Reason

    1 LinemandLinekareparallelandintersectedbyLinen Given

    2 15and26Iftwoparallellinesarecutbyatransversal,thenthecorrespondinganglesare

    3 13and24 VerticalAnglesare

    4 35and46TransitivePropertyofCongruence

    AlternateInteriorAnglesProofGiven:LinemandLinekareparallelandintersectedbyLinen

    Prove:3546

    123 4

    567 8

    k

    m

    n

  • 99

    ConverseofAlternateInteriorAnglesTheorem

    Iftwolinesarecutbyatransversalandthealternateinterioranglesarecongruent,thenthelinesareparallel.

  • 100

    123 4

    567 8

    k

    m

    n

    AlternateExteriorAnglesTheorem

    Iftwoparallellinesarecutbyatransversal,thenthealternateexterioranglesarecongruent.

    AccordingtotheAlternateExteriorAnglesTheoremwhichanglesarecongruent?

    Ans

    wer

    AccordingtoAlternateExteriorAnglesTheoremthe

    followinganglesarecongruent:

    1728

  • 101

    AlternateExteriorAnglesTheorem

    SincetheprooffortheAlternateExteriorAnglesTheoremisverysimilartotheAlternateInteriorAnglesTheorem,youwillbecompletingthisproofasapartofyourHomeworkforthislesson.

  • 102

    ConverseofAlternateExteriorAnglesTheorem

    Iftwolinesarecutbyatransversalandthealternateexterioranglesarecongruent,thenthelinesareparallel.

  • 103

    123 4

    567 8

    k

    m

    n

    SameSideInteriorAnglesTheorem

    Iftwoparallellinesarecutbyatransversal,thenthesamesideinterioranglesaresupplementary.

    AccordingtotheSameSideInteriorAnglesTheoremwhichpairsofanglesaresupplementary?

    Answ

    er

    Ans

    wer

    AccordingtoSameSideInteriorAnglesTheoremthe

    followinganglesaresupplementary:

    m3+m6=180m4+m5=180

  • 104

    SameSideInteriorAnglesProof

    Given:Linesmandkareparallelandintersectedbylinen

    Prove:3&6aresupplementaryand4&5aresupplementary

    123 4

    567 8

    k

    m

    n

  • 105

    28 Whichreasonappliestostep1?

    Statement Reason

    1 Linesmandkareparallelandintersectedbylinen ?

    2 m3+m6=180m4+m5=180 ?

    3 ? Definitionofsupplementarys

    123 4

    567 8

    k

    m

    nA DefinitionofsupplementaryB Euclid'sFifthPostulateC GivenD AlternateInterior sareE Corresponding sare A

    nswer

    C

  • 106

    29 Whichreasonappliestostep2?

    A DefinitionofsupplementaryB Euclid'sFifthPostulateC GivenD AlternateInterior sareE Corresponding sare

    Statement Reason

    1 Linesmandkareparallelandintersectedbylinen ?

    2 m3+m6=180m4+m5=180 ?

    3 ? Definitionofsupplementarys

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 107

    30 Whichstatementshouldbeinstep3?

    A B C D E

    Statement Reason

    1 LinemandLinekareparallelandintersectedbyLinen ?

    2 Thesumsofm3andm6andofm4andm5are180. ?

    3 ?Definitionofsupplementary

    angles

    123 4

    567 8

    k

    n

    m

    3and6aresupplementary6and5aresupplementary2and6aresupplementary4and5aresupplementary3and5aresupplementary A

    nswer

  • 108

    Statement Reason

    1 Linesmandkareparallelandintersectedbylinen Given

    2 m3+m6=180m4+m5=180 Euclid'sFifthPostulate

    3 3and6aresupplementary4and5aresupplementary Definitionofsupplementarys

    SameSideInteriorAnglesProof

    Given:LinemandLinekareparallelandintersectedbyLinen

    Prove:3&6aresupplementaryand4&5aresupplementary

    123 4

    567 8

    k

    m

    n

  • 109

    ConverseofSameSideInteriorAnglesTheorem

    Iftwolinesarecutbyatransversalandthesamesideinterioranglesaresupplementary,thenthelinesareparallel.

  • 110

    123 4

    567 8

    k

    m

    n

    SameSideExteriorAnglesTheoremIftwoparallellinesarecutbyatransversal,thenthesamesideexterioranglesaresupplementary.

    AccordingtotheSameSideExteriorAnglesTheoremwhichanglesaresupplementary?

    Ans

    wer

    AccordingtoSameSideExteriorAnglesTheoremthefollowinganglesare

    supplementary:

    m2+m7=180m1+m8=180

  • 111

    SameSideExteriorAnglesProof

    Given:LinesmandkareparallelandintersectedbyLinen

    Prove:2&7aresupplementary

    Inprovingthat2&7aresupplementarywearetherebyprovingthat1&8aresupplementaryasthesameargumentsapplytobothpairsofangles.

    123 4

    567 8

    k

    m

    n

  • 112

    31 Whichreasonappliestostep1?A Definitionofsupplementary sB SubstitutionpropertyofequalityC GivenD sthatformalinearpairaresupplementary

    Statement Reason

    1 LinemandLinekareparallelandintersectedbyLinen ?

    2 ? Samesideinterioranglesaresupplementary

    3 ? Anglesthatformalinearpairaresupplementary4 26and37 ?5 2&7aresupplementary ?

    E ssupplementarytothesame are

    123 4

    567 8

    k

    m

    n

    Ans

    wer

    C

  • 113

    Statement Reason

    1 LinemandLinekareparallelandintersectedbyLinen ?

    2 ? Samesideinterioranglesaresupplementary

    3 ? Anglesthatformalinearpairaresupplementary4 26and37 ?5 2&7aresupplementary ?

    32 Whichstatementismadeinstep2?

    A 2&1aresupplementaryB 7&8aresupplementaryC 3&6aresupplementaryD 4&5aresupplementaryE 5&8aresupplementary

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 114

    33 Whichstatementismadeinstep3?A B C D E

    2&3aresupplementary1&3aresupplementary6&8aresupplementary6&7aresupplementary7&1aresupplementary

    Statement Reason

    1 LinemandLinekareparallelandintersectedbyLinen ?

    2 ? Samesideinterioranglesaresupplementary

    3 ? Anglesthatformalinearpairaresupplementary4 26and37 ?5 2&7aresupplementary ?

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 115

    Statement Reason

    1 LinemandLinekareparallelandintersectedbyLinen ?

    2 ? Samesideinterioranglesaresupplementary

    3 ? Anglesthatformalinearpairaresupplementary4 26and37 ?5 2&7aresupplementary ?

    34 Whichreasonappliestostep4?A Definitionofsupplementary sB SubstitutionpropertyofequalityC GivenD sthatformalinearpairaresupplementary

    E ssupplementarytothesame are

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 116

    35 Whichreasonappliestostep5?

    Statement Reason

    1 Linesmandkareparallelandintersectedbylinen ?

    2 ? Samesideinterioranglesaresupplementary

    3 ? Anglesthatformalinearpairaresupplementary4 26and37 ?

    5 2&7aresupplementary ?

    A DefinitionofsupplementarysB SubstitutionpropertyofequalityC GivenD Anglesthatformalinearpairaresupplementary

    E ssupplementarytothesameare

    123 4

    567 8

    k

    m

    n

    Ans

    wer

  • 117

    SameSideExteriorAnglesProof

    Statement Reason

    1 Linesmandkareparallelandintersectedbylinen Given

    2 3&6aresupplementary Samesideinterioranglesaresupplementary

    3 2&3aresupplementary6&7aresupplementaryAnglesthatformalinearpairaresupplementary

    5 26and37Anglessupplementarytothesameanglearecongruent

    6 2&7aresupplementary SubstitutionPropertyofEquality

    Given:LinemandLinekareparallelandintersectedbyLinen

    Prove:2&7aresupplementary(andtherebythat1&8areaswell)

    123 4

    567 8

    k

    m

    n

  • 118

    ConverseofSameSideExteriorAnglesTheorem

    Iftwolinesarecutbyatransversalandthesamesideexterioranglesaresupplementary,thenthelinesareparallel.

  • 119

    PropertiesofParallelLines

    ReturntoTableofContents

  • 120

    PropertiesofParallelLines

    Thereareseveraltheoremsandpostulatesrelatedtoparallellines.Atthistime,pleasegotothelabtitled,"PropertiesofParallelLines".

    Clickheretogotothelabtitled,"PropertiesofParallelLines"

    MathPractic

    e

    ThislabaddressesMP1,MP3,MP4,MP5,MP6,MP7&MP8

    https://njctl.org/courses/math/geometry/parallel-lines/attachments/properties-of-parallel-lines-2/https://njctl.org/courses/math/geometry/parallel-lines/properties-of-parallel-lines/

  • 121

    PropertiesofParallelLines

    123 4

    567 8

    k

    n km

    m

    Example:Ifm4=54,findthem8.

    Explainyouranswer.

    Ans

    wer

    AccordingtoCorrespondingAnglesPostulate48,therefore

    m8=54.

    ThisexampleaddressesMP1,MP2&MP3

  • 122

    PropertiesofParallelLines

    Example:Ifm3=125,findthem5.

    Explainyouranswer.

    123 4

    567 8

    k

    n km

    m

    Ans

    wer

    ThisexampleaddressesMP1,MP2&MP3

  • 123

    PropertiesofParallelLines

    Example:Ifm2=78,findthem8.

    Explainyouranswer.

    123 4

    567 8

    k

    m

    n km

    Ans

    wer

    ThisexampleaddressesMP1,MP2&MP3

  • 124

    PropertiesofParallelLines

    Example:Ifm3=163,findm6.Explainyouranswer.

    123 4

    567 8

    k

    m

    n km

    Ans

    wer

    ThisexampleaddressesMP1,MP2&MP3

  • 125

    PropertiesofParallelLines

    Namealloftheanglescongruentto1.

    123 4

    567 8

    k

    m

    n km

    Ans

    wer

    1357

  • 126

    PropertiesofParallelLines

    Namealloftheanglessupplementaryto1.

    123 4

    567 8

    k

    m

    n km

    Ans

    wer

    1issupplementarytoangles:2,4,6,and8.

  • 127

    36 Findalloftheanglescongruentto5.A 1B 4C 8D alloftheabove

    1 23 4

    5 687

    jm

    j

    m

    k

    Ans

    wer

    D

  • 128

    37 Findthevalueofx.

    j

    m(5x+30)

    120

    jm

    k

    Ans

    wer

  • 129

    38 Findthevalueofx.

    j

    m(1.5x+40)

    110

    jmk

    Ans

    wer

  • 130

    39 Ifthem4=116thenm9=_____?

    kmnp

    n p

    2 13 4

    567 8

    91011 12

    131415 16

    k

    m

    Ans

    wer

    64

  • 131

    40 Ifthem15=57,thenthem2=_____.

    A 57B 123C 33D noneoftheabove

    kmnp

    n p

    2 13 4

    567 8

    91011 12

    131415 16

    k

    m

    Ans

    wer

  • 132

    Withthegivendiagram,notransversalexistsbutwecanextendoneofthelinestomakeatransversal.

    ExtendingLinestoMakeTransversals

    131

    1

    41

    Findm1.

  • 133

    Thenfillintheanglewhichiscorrespondingtothe131angle.Whichanglecorrespondstothe131?

    ExtendingLinestoMakeTransversals

    131

    1

    41

    Findm1.

    Ans

    wer

    ThequestiononthisslideaddressesMP7.

    Thetopangleinthesetof4anglesinthefigure(ontherightsideofthefigure).

  • 134

    Thenfindthemeasurementoftheangleadjacentto131thatisinsideofthetriangle.Whatisthemeasurementofthisangle?Explainyouranswer.

    ExtendingLinestoMakeTransversals

    131

    1

    41

    131

    Findm1.

    Ans

    wer

    ThequestionsonthisslideaddressMP2&MP3.

    49degreesTheanglesarealinearpair,

    whichmakesthemsupplementary.

  • 135

    Asyoumayrecall,thethirdangleinthetrianglemustmakethesumoftheanglesequalto180.Whatisthemeasurementofthe3rdangleinthetriangle?

    ExtendingLinestoMakeTransversals

    131

    1

    41

    13149

    Findm1.

    Ans

    wer

    ThequestiononthisslideaddressesMP2.

  • 136

    And,finallythatangle1issupplementarytothat90angle.Whatism1?

    ExtendingLinestoMakeTransversals

    131

    1

    41

    13149

    90

    Findm1.

    MathPractic

    e

    ThequestiononthisslideaddressesMP2.

  • 137

    m1=90

    ExtendingLinestoMakeTransversals

    131

    1

    41

    13149

    90

    Findm1.

  • 138

    Findthevaluesofxandy.

    DoubleTransversals

    132

    x

    (4y+12)

    Ans

    wer

    AdditionalQ'sthataddressMP's:Whatinformationareyougiven?(MP1)Whatdoyouneedtofind?(MP1)Createanequationtorepresenttheproblem.(MP2)Howaretheanglesw/theexpressionsrelatedthe132angle?(MP7)

  • 139

    (14x+6) 66

    2z

    (3y6)

    Findthevaluesofx,y,andz.

    TransversalsandPerpendicularLines

    Ans

    wer

  • 140

    41 Findthem1.

    1

    126

    110

    Ans

    wer

  • 141

    42 Findthevalueofx.

    (3x)

    54

    A 12B 54C 42D 18

    Ans

    wer

  • 142

    43 Findthevalueofx.

    (2x3)

    (4x61) Ans

    wer

  • 143

    122

    (16x+10)

    44 Findthevalueofx.

    Ans

    wer

  • 144

    Ifm3=56,findthem7thatmakeslineskandmparallel.

    Explainyouranswer.

    123 4

    567 8

    k

    m

    n

    ProvingLinesareParallel

    Ans

    wer

    AccordingtotheConverseoftheCorresponding

    AnglesTheorem,ifm3=m7,thenkm.

    Therefore,ifm3=56,thenm7=56.

    ThisexampleaddressesMP1,MP2&MP3

  • 145

    Ifm4=110,findthem6thatmakeslineskandmparallel.

    Explainyouranswer.

    ProvingLinesareParallel

    Ans

    wer

    AccordingtotheConverseoftheAlternateInteriorAnglesTheorem,ifm4=

    m6,thenkm.Therefore,ifm4=110,thenm6=110.

    ThisexampleaddressesMP1,MP2&MP3

    123 4

    567 8

    k

    m

    n

  • 146

    Ifm1=48,findthem7thatmakeslineskandmparallel.

    Explainyouranswer.

    ProvingLinesareParallel

    Ans

    wer

    AccordingtotheConverseoftheAlternateExteriorAnglesTheorem,ifm1=m7,thenkm.Ifm1=48,

    thenm7=48

    ThisexampleaddressesMP1,MP2&MP3

    123 4

    567 8

    k

    m

    n

  • 147

    Ifm5=54,findthem4thatmakeslineskandmparallel.

    Explainyouranswer.

    ProvingLinesareParallel

    123 4

    567 8

    k

    m

    n

    Ans

    wer

    AccordingtotheConverseoftheSameSideAnglesTheorem,ifm5+m4=

    180,thenkm.Therefore,ifm5=54,thenm4=126 .

    ThisexampleaddressesMP1,MP2&MP3

  • 148

    45 Whichstatementwouldshowlineskandmparallel?

    123 4

    567 8

    k

    m

    n

    A m2=m4B m5+m6=180

    C m3=m5D m1+m5=90

    Ans

    wer

  • 149

    46 Inthisdiagram,whichofthefollowingistrue?

    12364 57

    132

    e f g

    h

    i

    A efB fgC hiD eg

    Ans

    wer

    D

  • 150

    47 IflinesaandbarecutbyatransversalwhichofthefollowingwouldNOTprovethattheyareparallel?

    A Correspondinganglesarecongruent.B Alternatneinterioranglesarecongruent.C Samesideinterioranglesarecomplementary.D Samesideinterioranglesaresupplementary.E Alloftheabove. An

    swer

    C

  • 151

    48 Findthevalueofxforwhichab.

    a

    bx

    115

    d

    Ans

    wer

  • 152

    49 Findthevalueofxwhichmakesab.

    (6x20)

    2x

    a

    b

    cd

    Ans

    wer

    x=25

  • 153

    50 Findthevalueofxforwhichmn.

    m

    n

    (14x10)

    (5x) Answ

    er

    10

  • 154

    51 Ifab,howcanweprovem1=m4?

    A CorrespondinganglestheoremB ConverseofcorrespondinganglestheoremC AlternateInterioranglestheoremD Converseofalternateinterioranglestheorem

    a b

    c1 4

    32

    Ans

    wer

    C

  • 155

    52 Ifm1=m3,howcanweproveab?

    A CorrespondinganglestheoremB ConverseofcorrespondinganglestheoremC AlternateInterioranglestheoremD Converseofalternateinterioranglestheorem

    a b

    c1 4

    32

    Ans

    wer

  • 156

    53 Givenm1=m2,m3=m4,whatcanweprove?(chooseallthatapply)

    A abB cdC lineaisperpendiculartolinecD linebisperpendiculartolined

    ab

    d

    12

    3

    4 5 c

    Ans

    wer

  • 157

    54 Givenab,whatcanweprove?

    A m1=m2B m1=m4C m2=m3D m1+m3=180

    a b

    c1 4

    32

    Ans

    wer

  • 158

    ConstructingParallelLines

    ReturntoTableofContents

    MathPractic

    e

    Thisentirelessonw/constructionsaddressesMP5

  • 159

    ParallelLineConstruction

    Constructinggeometricfiguresmeansyouareconstructinglines,angles,andfigureswithbasictoolsaccurately.

    Weuseacompass,andstraightedgeforconstructions,butwealsousesomepaperfoldingtechniques.

    Clickheretoseeananimatedconstructionofaparallellinethrough

    apoint.

    Constructionby:MathIsFun

    http://www.mathsisfun.com/geometry/construct-paranotline.html

  • 160

    Given:LineABandpointC,notontheline,drawasecondlinethatisparalleltoABandgoesthroughpointC.

    Therearethreedifferentmethodstoachievethis.

    Method1:CorrespondingAngles

    ParallelLineConstruction

    A

    C

    B

  • 161

    Thetheoryofthisconstructionisthatthecorrespondinganglesformedbyatransversalandparallellinesareequal.

    Tousethistheory,wewilldrawatransversalthroughCthatcreatesanacuteanglewithlineAB.

    ThenwewillcreateacongruentangleatC,onthesamesideofthetransversalastheacuteangleformedwithlineAB.

    Sincethesearecongruentcorrespondingangles,thelinesareparallel.

    A

    C

    B

    ParallelLineConstruction:Method1

  • 162

    Step1:DrawatransversaltoABthroughpointCthatintersectsABatpointD.AnacuteanglewithpointDasavertexisformed(themeasureoftheangleisnotimportant).

    ParallelLineConstruction:Method1

    A

    C

    BD

    TheangleCDBistheanglewewillreplicateatpointConthesamesideofthetransversal.

  • 163

    A

    C

    BD

    F

    E

    Step2:CenterthecompassatpointDanddrawanarcthatintersectsbothlines.Usingthesameradiusofthecompass,centeritatpointCanddrawanotherarc.LabelthepointofintersectiononthesecondarcF.

    0135Wearefollowingthe

    procedureweusedpreviouslytoconstructacongruentangle.

    ThisstepistomarkthesamedistancesfromDandfromC.

    ParallelLineConstruction:Method1

  • 164

    Step3:Setthecompassradiustothedistancebetweenthetwointersectionpointsofthefirstarc.

    A

    C

    BD

    F

    0

    118

    Thisreplicatesthedistancebetweenwherethearcintersectsthetwolegsoftheangleatthesamedistancefromthevertex.

    WhenthatisreplicatedatCtheangleconstructedwillbecongruentwiththeoriginalangle.

    ParallelLineConstruction:Method1

  • 165

    Step4:CenterthecompassatthepointFwherethesecondarcintersectslineDCanddrawathirdarc.

    A

    C

    BD

    F

    0

    118

    ParallelLineConstruction:Method1

    Thisassuresthatthearclengthforeachangleisidentical.

  • 166

    Step5:MarkthearcintersectionpointEanduseastraightedgetojoinCandE.

    A

    C

    BD

    F

    E

    ParallelLineConstruction:Method1

    CDB FCEthereforeABCE

  • 167

    Herearemyparallellineswithouttheconstructionlines.

    A BD

    C E

    ParallelLineConstruction:Method1

  • 168

    VideoDemonstratingConstructingParallelLineswithCorrespondingAngles

    usingDynamicGeometricSoftware

    Clickheretoseevideo

    http://youtu.be/OZwIX9kVp0M

  • 169

    Thetheoryofthisconstructionisthatthealternateinterioranglesformedbyatransversalandparallellinesareequal.

    Tousethistheory,wewilldrawatransversalthroughCthatcreatesanacuteanglewithlineAB.

    ThenwewillcreateacongruentangleatC,ontheoppositesideofthetransversalastheacuteangleformedwithlineAB.

    Sincethesearecongruentalternateinterioranglesthelinesareparallel.

    A

    C

    B

    ParallelLineConstruction:Method2

  • 170

    A B

    C

    Method2:AlternateInteriorAnglesGivenABandpointC,notontheline,drawasecondlinethatisparalleltoABandgoesthroughpointC.

  • 171

    A B

    C

    D

    Method2:AlternateInteriorAnglesStep1:DrawatransversaltolineABthroughpointCthatintersectslineABatpointD.AnacuteanglewithpointDasavertexisformed.

    TheangleCDBistheanglewewillreplicateatpointContheoppositesideofthetransversal.

  • 172

    A B

    C

    D

    F

    E

    Method2:AlternateInteriorAngles

    0 148

    Step2:CenterthecompassatpointDanddrawanarcthatintersectsbothlines,atpointsEandatF.Wearefollowingtheprocedureweusedpreviouslytoconstructacongruentangle.

    ThisstepistomarkthesamedistancefromDonbothlines.

  • 173

    A B

    C

    D

    F

    E

    G

    Method2:AlternateInteriorAngles

    0144

    Step3:Usingthesameradius,centerthecompassatpointCanddrawanarcthatpassesthroughlineDCatpointG.

    ThisreplicatesthesamedistancealongthetransversalandthenewlinethatwillbedrawnfromCaswasdoneforthedistancesfromD.

  • 174

    A B

    C

    D

    F

    E

    G

    H

    Method2:AlternateInteriorAnglesStep4:Again,withthesameradius,centerthecompassatpointGanddrawathirdarcwhichintersectstheearlierone,atH.

    0

    144

    Thisnowfindsthatsamedistancefromwherethearcintersectsthetransversalandthenewlineaswasthecaseforthetransversalandtheoriginalline.

  • 175

    A B

    C

    D

    F

    E

    G

    H

    Step5:DrawlineCH,whichwillbeparalleltolineABsincetheiralternateinterioranglesarecongruent.

    Method2:AlternateInteriorAngles

    0

    144

    SinceanglesHCGandBDFarecongruentandarealternateinteriorangles,thelinesareparallel.

  • 176

    A B

    C

    D

    H

    Herearethelineswithouttheconstructionstepsshown.

    Method2:AlternateInteriorAngles

  • 177

    VideoDemonstratingConstructingParallelLineswithAlternateInteriorAngles

    usingDynamicGeometricSoftware

    Clickheretoseevideo

    http://youtu.be/p2iPjRX3LOM

  • 178

    A B

    C

    Method3:AlternateExteriorAnglesGivenlineABandpointC,notontheline,drawasecondlinethatisparalleltolineABandgoesthroughpointC.

  • 179

    B

    C

    DA

    Method3:AlternateExteriorAnglesStep1:DrawatransversaltolineABthroughpointCthatintersectslineABatpointD.AnacuteanglewithpointDasavertexisformed.

  • 180

    A B

    C

    D

    E

    Method3:AlternateExteriorAnglesStep2:CenterthecompassatpointDanddrawanarctointersectlinesABandDContheoppositesideofpointCatAandE. 0

    168

  • 181

    A B

    C

    D

    F

    E

    Method3:AlternateExteriorAnglesStep3:KeepingtheradiusthesamedrawanarccenteredonCthatintersectslineDCaboveC,atF.

    0

    168

  • 182

    A B

    C

    D

    F

    E

    G

    Method3:AlternateExteriorAnglesStep4:StillkeepingtheradiusthesamedrawanarccenteredonFthatintersectsthearccenteredonC,atH.

    0168

  • 183

    A B

    C

    D

    F

    E

    G

    Step5:DrawlineCE,whichisparalleltolineABsincethealternateexterioranglesformedbythetransversalarecongruent.

    Method3:AlternateExteriorAngles

    ADGECFthereforeABCE

  • 184

    A B

    C E

    Herearethelineswithouttheconstructionlines.Method3:AlternateExteriorAngles

  • 185

    VideoDemonstratingConstructingParallelLineswithAlternateExterior

    AnglesusingDynamicGeometricSoftware

    Clickheretoseevideo

    http://youtu.be/GnZ5E7i3qaQ

  • 186

    ParallelLineConstructionUsingPattyPaper

    Step1:Drawalineonyourpattypaper.Labelthelineg.DrawapointnotonlinegandlabelthepointB.

    gB

  • 187

    gB

    ParallelLineConstructionUsingPattyPaper

    Step2:FoldyourpattypapersothatthetwopartsoflineglieexactlyontopofeachotherandpointBisinthecrease.

  • 188

    Step3:Openthepattypaperanddrawalineonthecrease.Labelthislineh.

    ParallelLineConstructionUsingPattyPaper

    gB

    h

  • 189

    Step4:ThroughpointB,makeanotherfoldthatisperpendiculartolineh.

    ParallelLineConstructionUsingPattyPaper

    gB

    h

  • 190

    Step5:Openthepattypaperanddrawalineonthecrease.Labelthislinei.

    Becauselinesiandgareperpendiculartolinehtheyareparalleltoeachother.Thereforelineilineg.

    ParallelLineConstructionUsingPattyPaper

    gB

    h

    i

  • 191

    VideoDemonstratingConstructingaParallelLineusingMenuOptionsof

    DynamicGeometricSoftware

    Clickheretoseevideo2

    Clickheretoseevideo1

    http://youtu.be/sBJBWp-61l0http://youtu.be/KiURcVkRGx0

  • 192

    C

    A B

    E

    D

    F

    G

    55 Thelinesinthediagrambelowareparallelbecauseofthe:A AlternateInteriorAnglesTheoremB AlternateExteriorAnglesTheoremC SameSideAnglesTheoremD CorrespondingAnglesPostulate

    Ans

    wer

    0109

  • 193

    56 Thelinesbelowareshownparallelbythe:

    A AlternateInteriorAnglesTheoremB AlternateExteriorAnglesTheoremC SameSideAnglesTheoremD CorrespondingAnglesPostulate

    C

    A

    E

    D

    F

    G

    Ans

    wer

    A

  • 194

    57 Thebelowlinesareshownparallelbythe:A AlternateInteriorAnglesTheoremB AlternateExteriorAnglesTheoremC SameSideAnglesTheoremD CorrespondingAnglesPostultate

    C

    AD

    FG

    E

    Ans

    wer

  • 195

    PARCCSampleTestQuestions

    TheremainingslidesinthispresentationcontainquestionsfromthePARCCSampleTest.Afterfinishingunit3,youshouldbeabletoanswerthesequestions.

    GoodLuck!

    ReturntoTableofContents

  • 196

    PARCCSampleTestQuestions

    PARCCReleasedQuestion(EOY)

    Topic:ParallelLines&Proofs

    http://parcc.pearson.com/practice-tests/math/

  • 197

    58 CBDBFE

    A GivenB DefinitionofcongruentanglesC VerticalanglesarecongruentD ReflexivepropertyofcongruenceE SymmetricpropertyofcongruenceF Transitivepropertyofcongruence

    BA

    D

    E

    F

    G

    C

    H

    Inthefigureshown,LineCFintersectslinesADandEHatpointsBandF,respectively.

    Given:CBDBFEProve:ABFBFE

    Ans

    wer

    A

  • 198

    59 CBDABF

    A GivenB DefinitionofcongruentanglesC VerticalanglesarecongruentD ReflexivepropertyofcongruenceE SymmetricpropertyofcongruenceF Transitivepropertyofcongruence

    BA

    D

    E

    F

    G

    C

    H

    Inthefigureshown,LineCFintersectslinesADandEHatpointsBandF,respectively.

    Given:CBDBFEProve:ABFBFE

    Ans

    wer

    C

  • 199

    60 ABFBFEA GivenB DefinitionofcongruentanglesC VerticalanglesarecongruentD ReflexivepropertyofcongruenceE SymmetricpropertyofcongruenceF Transitivepropertyofcongruence

    BA

    D

    E

    F

    G

    C

    H

    Inthefigureshown,LineCFintersectslinesADandEHatpointsBandF,respectively.

    Given:CBDBFEProve:ABFBFE

    Ans

    wer

    F

  • 200

    BA

    D

    E

    F

    G

    C

    H

    Inthefigureshown,LineCFintersectslinesADandEHatpointsBandF,respectively.

    Given:CBDBFEProve:ABFBFE

    Completedproofshownbelow.

    Statement Reason

    1 CBDBFE Given

    2 CBDABF VerticalAnglesarecongruent

    3 ABFBFE Transitivepropertyofcongruence

  • 201

    PARCCSampleTestQuestions

    Circlethereasonthatsupportseachlineoftheproof.

    PARCCReleasedQuestion(EOY)

    Topic:ParallelLines&Proofs

    http://parcc.pearson.com/practice-tests/math/

  • 202

    61 mCBD=mBFEA GivenB AnglesthatformalinearpairaresupplementaryC AnglesthatareadjacentaresupplementaryD ReflexivepropertyofequalityE SubstitutionpropertyofequalityF Transitivepropertyofequality

    BA

    D

    E

    F

    G

    C

    H

    InthefigureshownLineCFintersectslinesADandEHatpointsBandF,respectively.

    Given:mCBD=mBFEProve:mBFE+ mDBF=180

    Ans

    wer

    A

  • 203

    62 mCBD+mDBF=180

    BA

    D

    E

    F

    G

    C

    H

    InthefigureshownLineCFintersectslinesADandEHatpointsBandF,respectively.

    Given:mCBD=mBFEProve:mBFE+ mDBF=180

    A GivenB AnglesthatformalinearpairaresupplementaryC AnglesthatareadjacentaresupplementaryD ReflexivepropertyofequalityE SubstitutionpropertyofequalityF Transitivepropertyofequality

    Ans

    wer

    B

  • 204

    63 mBFE+mDBF=180

    A GivenB AnglesthatformalinearpairaresupplementaryC AnglesthatareadjacentaresupplementaryD ReflexivepropertyofequalityE SubstitutionpropertyofequalityF Transitivepropertyofequality

    BA

    D

    E

    F

    G

    C

    H

    InthefigureshownLineCFintersectslinesADandEHatpointsBandF,respectively.

    Given:mCBD=mBFEProve:mBFE+ mDBF=180

    Ans

    wer

    E

  • 205

    BA

    D

    E

    F

    G

    C

    H

    InthefigureshownLineCFintersectslinesADandEHatpointsBandF,respectively.

    Given:mCBD=mBFEProve:mBFE+mDBF=180

    Statement Reason

    1 mCBD=mBFE Given

    2 mCBD+mDBF=180Anglesthatformalinearpairaresupplementary

    3 mBFE+mDBF=180 SubstitutionPropertyofEquality

  • 206

    64 PARTAConsiderthepartialConstructionofalineparalleltorthroughpointQ.whatwouldbethefinalstepintheconstruction?

    A DrawalinethroughPandSB DrawalinethroughQandSC DrawalinethroughTandSD DrawalinethroughWandS

    Thefigureshowsliner,pointsPandTonliner,andpointQnotonliner.AlsoshownisrayPQ.

    rTP

    Q

    rTP

    Q

    W

    S

    Ans

    wer

    PARCCReleasedQuestion(EOY)

    http://parcc.pearson.com/#

  • 207

    65 PARTBOncetheconstructioniscomplete,whichofthereasonslistedcontributetoprovingthevalidityoftheconstruction?

    A Whentwolinesarecutbyatransversalandthecorrespondinganglesarecongruent,thelinesareparallel.

    B Whentwolinesarecutbyatransversalandtheverticalanglesarecongruent,thelinesareparallel.

    C Definitionofsegmentbisector.D Definitionofananglebisector.

    Thefigureshowsliner,pointsPandTonliner,andpointQnotonliner.AlsoshownisrayPQ.

    rTP

    Q

    rTP

    Q

    W

    S

    Ans

    wer

    A

    PARCCReleasedQuestion(EOY)

    http://parcc.pearson.com/#

  • 208

    66 Thediagramrepresentsaportionofasmallcity.MapleStreetandPineStreetrunexactlyeasttowest.Oakavenuerunsexactlynorthtosouth.Allofthestreetsremainstraight.

    A BirchStreetandElmStreetintersectatrightangles.

    B MapleStreetandPineStreetareparallel.

    C Ifmoreofthemapisshown,ElmStreetandOakAvenuewillnotintersect.

    D PineStreetintersectsbothBirchStreetandElmStreet.E OakAvenueandMapleStreetareperpendicular.

    Question1/7

    PARCCReleasedQuestion(PBA)

    Topic:Lines:Intersecting,Parallel&Skew

    Whichstatementsmustbetruebasedonlyonthegiveninformation?Selectallthatapply.

    Ans

    wer

    http://parcc.pearson.com/#

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