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Parallelogram

A quadrilateral whose opposite sides are parallel

The opposite sides of a parallelogram are parallel.

A diagonal of a parallelogram divides it into two congruent triangles.

The opposite sides of a parallelogram are congruent.

The opposite angles of a parallelogram are congruent.

The consecutive angels of a parallelogram are supplementary.

The diagonals of a parallelogram bisect each other.

Five ways to prove a quadrilateral is a Parallelogram

1. A quadrilateral is a parallelogram if its opposite sides are parallel.

2. A quadrilateral is a parallelogram if its opposite sides are congruent.

3. A quadrilateral is a parallelogram if two sides are congruent and parallel.

4. A quadrilateral is a parallelogram if its opposite angles are congruent.

5. A quadrilateral is a parallelogram if its diagonals bisect each other.

Rectangle

An equiangular parallelogram

Rhombus

An equilateral parallelogram

Square

An equilateral and equiangular parallelogram