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.

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.

Each side of the Great Pyramid rises at an angle of 51.5 degrees to the top. Not only that, each of the sides are aligned almost exactly with true north, south, east, and west. For a pyramid to ...