By the definition of a , AD ||BC and AB||DC.
Using, AD as a transversal, ZA and are same-
side interior angles, so they are
Using side as a transversal, zB and Care
same-side interior angles, so they are supplementary
Using AB as a transversal, ZA and zB are same-side
interior angles, so they are supplementary
Therefore, ZA is congruent to 2C because they are
supplements of the same angle. Similarly, zB is
congruent to