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