PLANE G
EOMETRY
UNIT 1
– CHAPT
ER 1
SE
CT
I ON
1. 1
– I DE
NT
I FY
PO
I NT
S, L
I NE
S, A
ND
PL
AN
ES
DA
Y 1
SECTION 1.1 NOTES
Undefined Terms – Vocabulary without a formal definition, but overall agreement with what the term means.
Point – representation of a unique location in space. It has no dimension.
Line – connection of an infinite number of points. It has one dimension.
P
A B Cl
LINE NOTATION:Line l, Line AB ( AB ), Line ( BC ), or Line AC ( AC )
SECTION 1.1 NOTES
Compare and Contrast:
Line – Infinite in length, extends endlessly in opposite directions.
Segment – Finite portion of a line that begins and ends at endpoints (points on that line).
Ray – Infinitely long portion of a line that begins at an initial point and extends endlessly in one direction.
A B
A
AB
B
A B
AB
ABRAY NOTATION:
Point with no arrow head is called endpoint, always list endpoint first and always draw arrow pointing right.
Endpoint
SECTION 1.1 NOTES
Extension:
Opposite Rays – two rays that share the same endpoint but extend in exactly opposite directions. They =alwys form a straight line.
What are the opposite rays for the image given?
A IH
HA
Endpoint
HI
SECTION 1.1 NOTES
Plane – a flat surface that contains an infinite amount of lines and extends endlessly in two directions.
W
OC
M
PLANE NOTATION:Use any three points that lie on the plane and that do not lie in a line, or if a letter already represents it.
PLANE NOTATION:Plane M, or Plane COW, Plane WOC, Plane OCW
SECTION 1.1 NOTES
Collinear Points – points that all lie on the same line.
Coplanar Points – points that all lie on the same plane.
A B C D
G
OS
H
SECTION 1.1 NOTES
Identification, name:
The plane:
HOD, DOG, DGH
A Line:
AB, OB, HG, GO, …
A Segment:
GO, AO, BO, HG, …
A Ray:
OG, GH, BA, AB, HG, …
A
B
D
G
O
H
SECTION 1.1 NOTES
Identification, Collinear or not?
A) B, D
B) C, E
C) A, D
D) B, F
E) F, E, D
F) A, E, D
G) D, B, C
H) C, E, F
E
F
A
B
C
D
YES
YES
YES
YES
NO
NO
YES
YES
SECTION 1.1 NOTES
Identification, Coplanar or not?
A) B, C, D
B) A, B, C
C) F, E, D
D) E, A, F
E) A, B, C, D
F) F, E, D, C
G) E, A, D, C
H) B, C, D, E, F
E
F
A
B
C
D
YES
YES
YES
YES
YES
YES
NO
YES
SECTION 1.1 NOTES
Intersections: 2 lines always intersect at a point (Figure 1) A line that does not lie on a plane can intersect a
plane at a point. (Figure 2)
W
O
CE
F
CM
P
Figure 1
Figure 2
Intersection Intersecti
on
SECTION 1.1 NOTES
Intersections: (cont.) 2 Planes always
intersect at a line (Figure 3)
Figure 3
M
Q
a
Intersection: Line a
CHECK FOR UNDERSTANDING…TIME TO DRAW…Four coplanar points…three or which are
collinear.
A
B
C
D
CHECK FOR UNDERSTANDING…TIME TO DRAW…Two coplanar lines that do NOT intersect.
B C D
F E H
CHECK FOR UNDERSTANDING…TIME TO DRAW…Opposite rays AB and AC.
B CA
AB
Endpoint
AC
CHECK FOR UNDERSTANDING…TIME TO DRAW…Three planes that do not intersect.
M
A
B
CHECK FOR UNDERSTANDING…TIME TO DRAW…Three coplanar lines that intersect at the
same point.
B
CD
F
E
H
E
B
CHECK FOR UNDERSTANDING…TIME TO DRAW…Two planes that intersect one another.
M
Q
a
CHECK FOR UNDERSTANDING…TIME TO DRAW…Two lines that intersect and a third line that
does not intersect either of them.E
F
A
B
C
D
H
G
CHECK FOR UNDERSTANDING…TIME TO DRAW…Three lines that intersect at a point but are
not coplanar. A
B
D
G
O H
F
CONCEPT CHECK
P. 3-5
#1 – 7
“Guided Practice”
HOMEWORKP. 5-6
#3 - 26
(Omit #12)