Draw AEPTwith Eon TR.TEAPis a parallelogram.TAERbecause they are corresponding angles of parallel lines.TRbecause it is given, so AERR,because both are congruent to T. Therefore,AERis isosceles by the Converse of the IsoscelesTriangle Conjecture.TPEAbecause they areopposite sides of a parallelogram and AREAbecause AERis isosceles. Therefore,TPRAbecause both are congruent to EA.
