Which term is defined as two angles that form a straight line?

• A. End Behavior
• B. Rational
• C. Theorem
• D. Supplementary Angles

Answer: (D)

Two angles that form a straight line are supplementary angles. A straight line represents 180 degrees, so when two angles share a common vertex and their non-common sides lie along that straight line, their measures add up to 180. That sum defines them as supplementary. If they’re next to each other along the line, they form a linear pair, which is a specific type of supplementary angles. The other terms don’t describe this situation: end behavior is about how a graph behaves far out, rational refers to numbers that can be written as a ratio, and a theorem is a proven statement.