What do you call two angles that add up to 90 degrees?

Two angles that add up to 90 degrees are called complementary angles. This term is used specifically to describe pairs of angles whose measures sum to a right angle, which is defined as 90 degrees.

In geometry, understanding the properties of angles is fundamental, and recognizing complementary angles helps in various applications, from solving problems in trigonometry to constructing geometric figures.

The other terms do not pertain to the sum of angles equaling 90 degrees. Supplementary angles refer to pairs that add up to 180 degrees, acute angles are those that measure less than 90 degrees, and obtuse angles measure more than 90 degrees but less than 180 degrees. Knowing the definitions of these terms helps in distinguishing between different types of angles in geometric contexts.