Which term refers to two angles whose sum is 180 degrees?

• A. Adjacent
• B. Complementary
• C. Supplementary
• D. Linear

Answer: (C)

The term that refers to two angles whose sum is 180 degrees is supplementary. Supplementary angles are defined by this specific property, where when you add the measures of the two angles together, the total equals 180 degrees. This concept is fundamental in geometry and is essential when solving problems involving angles, particularly when working with parallel lines cut by a transversal or in various geometric figures.

For example, if one angle measures 120 degrees, the supplementary angle would measure 60 degrees, since 120 + 60 equals 180. This relationship can be applied in various practical situations, including construction and design, where understanding and calculating angles accurately is crucial.

Adjacent angles, on the other hand, refer to angles that share a common ray and vertex but do not overlap. Complementary angles are those whose sum equals 90 degrees, and linear angles are a specific case of supplementary angles that are formed when two lines intersect, creating a straight line. While all these terms relate to angles, only supplementary specifically describes the 180-degree sum property.