### Complementary Angles

Two angles are **complementary** if they add up to . Complementary angles **do not** have to be congruent or adjacent.

What if you were given two angles of unknown size and were told they are complementary? How would you determine their angle measures?

### Examples

#### Example 1

Find the measure of an angle that is complementary to if is .

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#### Example 2

Find the measure of an angle that is complementary to if is .

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#### Example 3

The two angles below are complementary. . What is ?

Because the two angles are complementary, they add up to . Make an equation.

#### Example 4

The two angles below are complementary. Find the measure of each angle.

The two angles add up to . Make an equation.

However, you need to find each angle. Plug back into each expression.

#### Example 5

Find the measure of an angle that is complementary to if is .

Because complementary angles have to add up to , the other angle must be .

### Review

Find the measure of an angle that is complementary to if is:

Use the diagram below for exercises 8-9. Note that .

- Name two complementary angles.

- If , find .

For 10-11, determine if the statement is true or false.

- Complementary angles add up to .
- Complementary angles are always .

### Review (Answers)

To see the Review answers, open this PDF file and look for section 1.7.

### Resources