How to prove a quadrilateral a parallelogram.
- 1. Prove both pairs of opposite sides congruent. [distance formula 4x]
- 2. Prove both pairs of opposite sides are parallel [slope formula 4x]
- 3. Prove one pair of opposite sides are both parallel and congruent [distance formua 2x, slope formula 2x]
- 4. Prove diagonals bisect each other. If both diagonals have the same midpoint, they bisect eachother. [midpoint formula 2x]