# Complementary Angles (Mathematics Lesson)

# Complementary Angles

Complementary angles are two angles which add up to a right angle.Two angles that add to 90° are are said to complement each other.

# A Real Example of Complementary Angles

Angles of 30° and 60° are complementary angles.30° + 60° = 90°.

# How to Find a Complementary Angle

**Question:**What angle complements the 53° angle below?

**Step 1:**The 53° angle and θ are complementary angles. They add up to 90°.

53° + θ = 90°.

**Step 2:**Subtract the 53° angle from 90°.

θ = 90° - 53° = 37°.

The complementary angle is 37°.

# Another Real Example of Complementary Angles

The slider below shows a real example of complementary angles in mathematics, where two angles in a right triangle are complementary:##### Curriculum

##### Interactive Test

**show**

##### Top Tip

**WHAT TYPES OF ANGLES ARE COMPLEMENTARY?**

**C**omplementary angles form a

**C**orner.

##### Note

**WHAT'S IN A NAME?**

Complementary comes from the Latin word 'complementum' meaning "filled up".

This is because an acute angle is filled up to form a right angle.

Don't confuse a complementary angle with a complimentary angle; which would be a free angle or an angle giving praise.