Complementary Angles

Two Angles are Complementary if they add up to 90 degrees (a Right Angle).

These two angles (40° and 50°) areComplementary Angles, because they add up to 90°. Notice that together they make a right angle.
But the angles don't have to be together. These two are complementary because 27° + 63° = 90°

Sumber : http://www.mathsisfun.com/geometry/complementary-angles.html