Page 876 - Algebra 1

Complementary and Supplementary Angles
Skills Bank Lesson 15
Two angles with measures that have a sum of 90° are complementary angles. Two angles with measures that have a sum of 180° are supplementary angles.
Identifying Complementary and Supplementary Angles
Example
1
a. Are ∠A and ∠B complementary or supplementary angles?
34°
A
B 56°
SOLUTION
m∠A + m∠B = 34° + 56° = 90° ∠A and ∠B are complementary.
Are ∠K and ∠L complementary or supplementary angles?
35°K
m∠K + m∠L = 35° + 125° = 160°
∠K and ∠L are neither complementary nor supplementary.
Finding Missing Angle Measures
b.
SOLUTION
L 125°
Example
2
a. ∠M and ∠N are supplementary angles. Find m∠N.
M 38° N SOLUTION
38° + m∠N = 180°
m∠N = 180° - 38°
m∠N = 142°
Skills Bank Practice
b. ∠E and ∠F are complementary angles. Find m∠F.
SOLUTION
67°
E
F
67° + m∠F = 90°
m∠F = 90° - 67°
m∠F = 23°
Classify each pair of angles as complementary or supplementary. Then find the missing angle measure.
a. b. c.
134°
28° x
d. ∠D and ∠E are complementary angles. If the measure of ∠D is 50°, what is the
66° x
measure of ∠E ?
e. ∠W and ∠T are supplementary angles. If the measure of ∠W is 50°, what is the measure of ∠T ?
x
Skills Bank 861
SKILLS BANK