A parallelogram is a 4-sided polygon with opposite sides parallel.
It has the following properties:
- Opposite sides are equal
- Diagonals bisect each other
- Opposite angles are equal
- Adjacent angles sum to 1800
- It has rotational symmetry of order at least 2.
- Its area is equal to its base multiplied by its vertical height
The set of rhombuses (rhombi) is a subset of the set parallelograms.