Two angles whose sum is 90 degrees are called what?

Two angles whose sum is 90 degrees are called what?

• A. Vertical angles
• B. Complementary angles
• C. Supplementary angles
• D. Adjacent angles

Answer: (B)

Two angles whose sum is 90 degrees are called complementary angles. This is because they together complete a right angle. A common way to see this is in a right triangle: the two non-right angles must add up to 90, so they are complementary. For example, 30 degrees and 60 degrees are complementary since they sum to 90. In contrast, vertical angles are opposite angles formed by intersecting lines and are equal to each other, not defined by a 90-degree total; supplementary angles sum to 180 degrees; and adjacent angles share a vertex and a side but can have any measures.

Two angles whose sum is 90 degrees are called complementary angles. This is because they together complete a right angle. A common way to see this is in a right triangle: the two non-right angles must add up to 90, so they are complementary. For example, 30 degrees and 60 degrees are complementary since they sum to 90. In contrast, vertical angles are opposite angles formed by intersecting lines and are equal to each other, not defined by a 90-degree total; supplementary angles sum to 180 degrees; and adjacent angles share a vertex and a side but can have any measures.