Answer:
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.
