Answer:
Step-by-step explanation:
Since ABCD is a parallelogram, we know that its opposite sides are parallel. That is, AB is parallel to CD and BC is parallel to DA.
To prove that AB = CD, we can use the fact that opposite sides of a parallelogram are congruent. That is, AB is congruent to DC. So, we can write:
AB = DC
Similarly, to prove that BC = DA, we can use the same fact. That is, BC is congruent to AD. So, we can write:
BC = AD
Therefore, we have proven that AB = CD and BC = DA, which shows that the opposite sides of the parallelogram ABCD are congruent.