What Are Parallelograms?

Parallelograms have two sets of equal and parallel sides

Parallelograms have four sides. The lines in each pair of opposite sides are parallel to each other and an equal length, leaving the shapes with two pairs of sides opposite sides. This also means that the angles in opposite corners are always congruent.

Each of the blue shapes below is a parallelogram. The red shape is not.

Area:

You can find the area of a parallelogram by multiplying $\text{base}\times\text{height}$, where $\text{base}$ is the length of one of the sides and $\text{height}$ is the distance between that side and the opposite side parallel to it.

You can think of $\text{height}$ as the length of an altitude from one of the sides to the other parallel side.

Relationship to other quadrilaterals:

Parallelograms are trapezoids with two pairs of parallel sides.

Rectangles are parallelograms with perpendicular sides.

Rhombi are parallelograms where all the sides are an equal length.

Squares are parallelograms with perpendicular, equal length sides.