## Identify Complementary and Supplementary Angles

### Complementary Angles: Learn

Two angles are *complementary* if the sum of their angles equals 90°
(they add up to a right angle).

If one angle is known, its complementary angle can be found by subtracting the measure of its angle from 90°.

Example: What is the complementary angle of 43°?

Solution: 90° - 43° = 47°

Two angles are *supplementary* if the sum of their angles equals 180°
(they add up to a straight line).

If one angle is known, its supplementary angle can be found by subtracting the measure of its angle from 180°.

Example: What is the supplementary angle of 43°?

Solution: 180° - 43° = 137°

### Complementary and Supplementary: Practice

#### Are the angles complementary, supplementary, or neither?

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Angle A is °Angle B is °

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