Question

Prove that if the opposite angles of a quadrilateral are equal, then the quadrilateral is a parallelogram.​

Answer 1

Theorem: In a parallelogram, opposite angles are equal. Conversely, if the opposite angles in a quadrilateral are equal, then it is a parallelogram. Thus, the two triangles are congruent, which means that ∠B = ∠D .Similarly, we can show that ∠A = ∠C . This proves that opposite angles in any parallelogram are equal