Answer:
Given as steps.
Explanation:
Step 2: Opposite angles of a parallelogram are Equal
Step 4 ( After " Definition of a parallelogram"): Given
Step 5: ASA congruency Property / Therom
Step 6: CPCTC
P.S: It is ASA congruency Therom as both angles are adjacent to the side they are trying to prove.
Hope It Helps!