Congruent line segments have the same length and line segments that have the same length are congruent. if two angles form a linear pair, then they are supplementary angles. if pont d lies in the interior of ∠ abc, then m∠abc + m∠dbc = m∠ abc if b is between a and c, a, b, and c are co-linear and ab + bc = ac. if two angles have the same measure as measured by ta protractor, then the angles are congruent. also, if two angles are congruent, then they have the same measure. 1. the segment addition postulate 2. the segment congruence postulate 3. angle addition postulate 4. angle congruence postulate 5. linear pair postulate