Geometry CBE Practice Exam

When two angles form a linear pair, they sit next to each other on a straight line and their noncommon sides form opposite rays. That arrangement fills the straight angle of 180 degrees, so the measures of the two angles add up to 180. This is what we call supplementary. So, the true statement is that their measures sum to 180 degrees. They do share a vertex and a side, but the defining property here is the 180-degree total. They’re not necessarily complementary (sum to 90) or congruent (equal in measure).