2.4 Vertical Angles

Definitions

Vertical angles – are not adjacent, and their sides are formed by two intersecting lines

1 and 3 are vertical angles 2 and 4 are vertical angles

12

34

Definitions

Linear pair – two adjacent angles whose noncommon sides are on the same line

5 and 6 are a linear pair

5 6

Noncommon side Noncommon side

common side

Vertical Angle, Linear Pair, or Neither?

1

2

3 4

5 6

Postulate 7 – Linear Pair Postulate

If two angles form a linear pair, then they are supplementary

m 1 + m 2 = 180˚

1 2

Use the Postulate

Find the measure of RSU› 118˚

R

62˚

S T

U

Theorem 2.3 - Vertical Angles Theorem

Vertical Angles are congruent 1 3 and 2 4

1 32

4

Use the Theorem

Find the measure of CED

50˚

DA

B C

E

Find Angle Measures

Find m 1, m 2, and m 3

1

3235˚

Use Algebra with Vertical Angles

Find the value of y (4y-42) = 2y -42 = -2y 21 = y

2y˚

(4y-42)˚

Guided Practice

Pg. 78 #1-8