What are Complementary Angles?

Complementary angles are two angles whose degree measurements added together equal 90 degrees, the equivalent of a right angle. For instance, in a right angled triangle, one of the three angles is, by definition, a 90 degree right angle. Therefore, since the three angles in a triangle always add up to 180 degrees, the remaining two angles would equal a total of 90 degrees. Those two angles would be called complementary angles.