Parallelograms: Area and Perimeter
A parallelogram is a quadrilateral in which both pairs of opposite sides are parallel .
It can be shown that opposite sides of parallelogram must be congruent , that opposite angles are also congruent , and that consecutive angles are supplementary .
The area of a parallelogram is given by the formula
,
where is the length of one base and is the height. (The figure below shows how to find the height of a parallelogram.)
The perimeter of a parallelogram is the sum of the lengths of its four sides.
For example, in the figure below, if is a parallelogram, then we know opposite sides are congruent, so and .
Therefore, the perimeter is or cm.