Complementary Angles (Mathematics Lesson)
Complementary AnglesComplementary 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 AnglesAngles of 30° and 60° are complementary angles.
30° + 60° = 90°.
How to Find a Complementary AngleQuestion: 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 AnglesThe slider below shows a real example of complementary angles in mathematics, where two angles in a right triangle are complementary:
Top TipWHAT TYPES OF ANGLES ARE COMPLEMENTARY?
Complementary angles form a Corner.
NoteWHAT'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.