**1. What is a complementary and supplementary angle?**

2. How do you find a complementary & supplementary angles?

2. How do you find a complementary & supplementary angles?

Before we define what we mean by complementary and supplementary angles, here is an important reminder about adjacent angles

**Adjacent angles**: Angles that share a vertex and a common side.

However angles do not have to be adjacent to be complementary or supplementary.

## Complementary Angles

**»**Two angles are complementary if the sum of their angles equals 90

^{0}.

**»**If one angle is known, its complementary angle can be found by subtracting the measure of its angle from 90^{0}.*: What is the complementary angle of 40*

**Example**^{0}?

*90*

**Solution**:^{0 }- 40

^{0}= 50

^{0}

**»**These two angles (40° and 50°) are**Complementary Angle**s, because they add up to 90°:**»**Notice that together they make a right angle.## Supplementary Angles

**»**Two angles are supplementary if the sum of their angles equals 180

^{0}.

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

^{0}.

*: What is the supplementary angle of 140*

**Example**^{0}?

**180**

*Solution:*^{0}- 140

^{0}= 40

^{0}

**»**These two angles (140° and 40°) are Supplementary Angles, because they add up to 180°:**»**Notice that together they make a straight angle.