# Parallelogram

A parallelogram is a quadrilateral, where the opposite angles and sides are pairwise equal.

The two diagonals of a parallelogram cross each other exactly in the midpoint of both of them.

## The circumference of a parallelogram

The circumference of a parallelogram is given by:

where a and b are the side lengths.

## Area of a parallelogram

There are two ways to calculate the area of a parallelogram:

Area with base and height given

where b is the base length and h is the height.

Area with side lengths and an angle given

where a and b are the side lengths and θ is the angle.

## Area and circumference of a parallelogram

 The one side length (a): The other side length (b): Height (h): Angle in degrees:

## Special types of parallelograms

If all sides are of equal length, the parallelogram is also called a rhombus.

If all angles of a parallelogram are equal, it’s also called a rectangle.

If all sides and angles of a parallelogram are equal, it’s also called a square.