Definition of a parallelogram
A parallelogram is a quadrilateral whose opposite sides are parallel.
Properties of a parallelogram
- The opposite angles of a parallelogram are equal.
- The opposite sides of a parallelogram are equal.
- The diagonals of a parallelogram bisect each other.
Tests for a parallelogram
A quadrilateral is a parallelogram if:
- its opposite angles are equal, or
- its opposite sides are equal, or
- one pair of opposite sides are equal and parallel, or
its diagonals bisect each other.