"If a quadrilateral is a parallelogram, then its opposite sides are equal".
Converse
"If both pairs of opposite sides of a quadrilateral are equal, then the quadrilateral is a parallelogram".
The converse statement stated above is a necessary condition for a quadrilateral to be a parallelogram. Similarly, we may formulate the following two other conditions for a quadrilateral to be a parallelogram.- "If the diagonals of a quadrilateral bisect each other, the quadrilateral is a parallelogram".
- "If either pair of opposite sides of a quadrilateral are equal and parallel, the quadrilateral is a parallelogram".
