Final answer:
Two angles that sum to 90 degrees are known as complementary. Supplementary angles sum to 180 degrees, while congruent angles are of equal measure. The term equivalent may imply similarity but is not a specific angle relationship.
Step-by-step explanation:
If two angles sum to 90 degrees, then they are complementary. Supplementary angles, on the other hand, are two angles that sum to 180 degrees. Congruent angles are angles that have the same measure. Equivalent is a more general term that can mean the same in some context but is not a specific type of angle relationship.
For instance, in trigonometry, understanding complementary angles is essential when working with sine and cosine, as they are complementary trigonometric functions. This means that the sine of an angle is equal to the cosine of its complement. For example, if we have a right triangle with angles of 30 and 60 degrees, we know that the sine of the 30-degree angle is equal to the cosine of the 60-degree angle.