noun

geometrya pair of angles whose measures add up to 90 degrees.
Complementary angles are a pair of angles whose measures add up to 90 degrees. When two angles are complementary, each angle is said to be the complement of the other. For example, if one angle measures 30 degrees, its complement would be an angle measuring 60 degrees, because 30 + 60 equals 90.
An angle is a measure of rotation or turning and is usually measured in degrees or radians. In geometry, an angle is the figure formed by two rays, sharing a common endpoint called the vertex.
Supplementary angles are a pair of angles that add up to 180 degrees. When two angles are supplementary, each angle is said to be the supplement of the other.