Common Core Geometry Practice Test

Supplementary angles are defined as two angles whose measures add up to exactly 180 degrees. This relationship is fundamental in geometry and is often used in various proofs and real-world applications.

For example, if one angle measures 70 degrees, the other must measure 110 degrees in order to sum to 180 degrees. This property is crucial in many geometrical constructions and in solving problems involving angle measures.

In contrast, adjacent angles may share a common side and vertex but do not necessarily sum to 180 degrees. Vertically opposite angles, formed by intersecting lines, are equal in measure rather than summing to a specific angle. Complementary angles add up to 90 degrees, not 180. Thus, the definition and characteristic of supplementary angles clearly highlight their unique property of summing to 180 degrees, confirming the correctness of the answer.