Page 79 - Math Course 3 (Book 2)

Angle Sum and Exterior Angle Theorems

Let’s Begin 38°

4 32°
5 3
1
Exterior Angles 2
41° 64° 29°
Example

m∠1 = 70, m∠2 =110, and
Find the measure of each numbered angle in the Answer
figure. m∠3 = 46, m∠4 = 102, m∠5 = 37.

38°
4 32°
5 3 Your Turn!
1
2 Interior Angles
41° 64° 29°
3

m∠1 = 32 + 38 Exterior Angle Theorem 2
45° 1 135° 4 5
= 70 Simplify. 85° 75°
If 2 ∠s form a linear pair, Find m∠1. Find m∠4.
m∠1 + m∠2 = 180
they are supplementary.
A. 50 A. 75
70 + m∠2 = 180 Substitution B. 45 B. 45
C. 120 C. 55
Subtract 70 from each
m∠2 = 110 D. 130 D. 85
side.
Answer Answer
m∠2 = m∠3 + 64 Exterior Angle Theorem

110 = m∠3 + 64 Substitution
Find m∠2. Find m∠5.
Subtract 64 from each
46 = m∠3 A. 50 A. 130
side.
If 2 ∠s form a linear pair, B. 45 B. 150
m∠4 + (m∠3 + 32) = 180 C. 120 C. 140
they are supplementary. D. 130 D. 120
m∠4 + (46 + 32) = 180 Substitution
Answer Answer

m∠4 + 78 = 180 Simplify.

Subtract 78 from each
m∠4 = 102 Find m∠3.
side.
A. 85
m∠5 + m∠4 + 41 = 180 Angle Sum Theorem B. 135
C. 45
m∠5 + 102 + 41 = 180 Substitution D. 75

m∠5 + 143 = 180 Simplify. Answer

Subtract 143 from each
m∠5 + = 37
side.
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