Answer: Proof
Step-by-step explanation: First, draw an auxiliary line from one angle to the angle opposite of it. (Make a diagonal of the parallelogram) Afterwards, the parallelogram will be split into two triangles. You can prove those 2 triangles congruent using alternate interior angles and then the ASA Postulate. After that because corresponding parts of congruent triangles are congruent, you know that A parallelogram's opposite sides are congruent. Hope that makes sense. All you'll have to do is put that into 2 column form