Complementary and supplementary angles are two important aspects of geometry that help people navigate and visualize space. However, unless you've dusted off your high school textbooks lately ...

Angles that add together to make a right angle are called complementary angles. If you know one complementary angle you can subtract it from 90° to find a missing angle.

Angles that add together to make a straight line are called supplementary angles. If you know one supplementary angle you can subtract it from 180° to find a missing angle.