chapter 2

Chapter 2

Points, Lines, and Angles

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Goal

Tell type of angle. Label angles. Measure angles.

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Review

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A? B? C?

Check

a ) ray b) line segment c) line

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angle a figure formed by the

intersection of two rays

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angle

Rays are called sides.

Point where sides intersect is called a vertex.

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angle examples non-examples

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Naming angles

Method 1 angle x angle y

Method 2 angle ABC angle CBA

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Degrees

List everything you can tell about this angle.

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-Angle – 2 rays that intersect -Sides – rays- Point where rays intersect – vertex- Angle ABC or CBA-Measured in degrees- 60 degrees

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Types of Angles

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Right Angle

Right angle an angle whose measure is 90 degrees

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right angles not right angles

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Acute angle acute angle

• an angle• whose measure • is less than 90

degrees

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acute angles not acute angles

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obtuse angle

obtuse angle• an angle • whose measure is • greater than 90

degrees but• less than 180 degrees

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Obtuse angle

Why are these obtuse angles?

Obtuse Angles Not Obtuse

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What type of angle? Why?

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Why type of angle? A? B? C? D? E? F?

a.acuteb.right anglec.obtused.acutee.right anglef. obtuse

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straight anglestraight angle an angle whose measure is 180 degrees

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straight angles not straight angles

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Page 28 number 1 - 101. measure of angle ARF

180 degreesstraight angle

2. measure of angle CRF120 degreesobtuse

3. measure of angle BRF155 degrees obtuse

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adjacent angles adjacent angle

two angles have same vertex share one ray

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List adjacent angles

Adjacent angles

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List adjacent angles

Adjacent angles

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adjacent angles not adjacent angles

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Page 29 1.Angle CDB is adjacent to angle _____

2. Angle TUV is adjacent to angle ____

3. Angle SRP is adjacent to angle ____

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vertical angles Vertical angles When two lines

intersect two pairs of

vertical angles are formed

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vertical angles Vertical angles are NOT adjacent.

Vertical angles have the same measure.

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Which angles are vertical?

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Which angles are adjacent?

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Page 30 Vertical angles 1. angle YPV and angle ____1. angle YPV and angle RPS2. angle QPR and angle _____3. angle QPR and angle VPT

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complementary angles two angles sum of measures is 90 degrees

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complementary angles What angles are complementary?

Why?

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complementary angles Are these angles complementary?

Why or Why not?

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complementary angles

not complementary angles

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Supplementary angles two angles sum of measures is 180 degrees

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Supplementary angles two angles sum of measures is 180 degrees

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Why are figure 1 and figure 2 both examples of supplementary angles?

supplementary angles

not supplementary angles

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Review of Angles

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Page 31

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