A rectangle has these properties: All angles are 90 degrees, opposite sides are equal in length, and opposite sides are parallel. A square can also be a rectangle. You can easily find the Area of a rectangle by following the simple equation in this article.

To calculate the area of a rectangle, multiply the adjacent sides together. Be careful not to multiply the opposite sides together. The formula to calculate the area is A = ab, where a and b are the adjacent sides of the rectangle.

Refer to the picture associated with this step to learn what sides in a rectangle are considered adjacent sides. They are marked as "a" and "b".

## Sciencing Video Vault

Now that you have learned how to find the adjacent sides of a rectangle, you can calculate its area. Let's say you have a rectangle with the following specifications. The opposite sides are 4 cm in length. The adjacent sides are 10 cm in length. Now let's plug these numbers into the math equation.

A = a*b, where a and b are adjacent sides of the rectangle. A = 4cm * 10cm A = 40cm squared

You have now calculated the area of a rectangle.