1. Complementary Angles have measures that add up to 90°.
Ch 2 Sect 3
Complementary and Supplementary Angles
Complementary Angles have measures that add up to 90°.
Supplementary Angles have measures that add up to 180°. 1

2. Ch 2 Sect 3
Complementary and Supplementary Angles
Adjacent Angles share a vertex and a side but do not share any interior points. (next-door neighbors ) 2

3. Because 22° + 158° = 180°, the angles are supplementary.
Example 1
Identify Complements and Supplements
Determine whether the angles are complementary, supplementary, or neither. a. b. c.
SOLUTION a.
Because 22° + 158° = 180°, the angles are supplementary. b.
Because 15° + 85° = 100°, the angles are neither complementary nor supplementary. c.
Because 55° + 35° = 90°, the angles are complementary. 3

4. Checkpoint
Identify Complements and Supplements
Determine whether the angles are complementary, supplementary, or neither. 1.
ANSWER
neither 2.
ANSWER
complementary 3.
ANSWER
supplementary

5. A is a complement of C, and mA = 47°. Find mC. a.
Example 3
Measures of Complements and Supplements
A is a complement of C, and mA = 47°. Find mC. a. b.
P is a supplement of R, and mR = 36°. Find mP.
SOLUTION a.
A and C are complements, so their sum is 90°. b.
P and R are supplements, so their sum is 180°.
mA + mC = 90°
mP + mR = 180°
47° + mC = 90°
mP + 36° = 180°
47°+ mC – 47° = 90° – 47°
mP + 36° – 36° = 180° – 36°
mC = 43°
mP = 144° 5

6. B is a complement of D, and mD = 79°. Find mB. 4.
Checkpoint
Measures of Complements and Supplements
B is a complement of D, and mD = 79°. Find mB. 4.
ANSWER
11° 5.
G is a supplement of H, and mG = 115°. Find mH.
ANSWER
65°

7. Tell whether the numbered angles are adjacent or nonadjacent.
Example 2
Identify Adjacent Angles
Tell whether the numbered angles are adjacent or nonadjacent. a. b. c.
SOLUTION a.
Because the angles do not share a common vertex or side, 1 and 2 are nonadjacent. b.
Because the angles share a common vertex and side, and they do not have any common interior points, 3 and 4 are adjacent. c.
Although 5 and 6 share a common vertex,
they do not share a common side. Therefore,
5 and 6 are nonadjacent. 7

8. Ch 2 Sect 3
Find k. 2k
3k + 10

9. Ch 2 Sect 3
Name a straight angle.
Name 2 congruent supplementary angles.
Name 2 angles that are supplementary but not congruent.
Name 2 complementary angles.

10. Ch 2 Sect 3
Homework: Page #1-24 and #35