Which criteria alone are sufficient to prove that a quadrilateral is a parallelogram? Hints: A parallelogram is a quadrilateral in which both pairs of opposite sides are parallel. Parallel lines have equal slopes.
1 pair of congruent opposite sides
2 pairs of congruent opposite sides
1 pair of congruent opposite angles
2 pairs of congruent opposite angles
1 diagonal is bisected by the other
both diagonals bisect each other
1 pair of parallel and congruent opposite sides