Geometry Help

Area of a Rectangle

Today we are going to calculate the area of a rectangle. First let us define what a rectangle is. Then we are going to calculate the area of a rectangle.

What is a rectangle?

A rectangle is one of the simplest geometrical shape consisting of 4 sides. But, not just any old sides, the opposite sides of a rectangle must be parallel to each other as well as having the same length. An example of a rectangle is shown here. As you can see, the left side and the right side are labeled a because they are parallel and have the same length. The top and bottom sides are labelled b because they also have the same length and are parallel to each other.


Between side a and b of the rectangle, you see the little square. This little square indicates that side a and b are perpendicular to each other which is another property of a rectangle; perpendicular sides. Now let us calculate the area of a rectangle.

How to calculate the area of a rectangle?

The area of a rectangle is simply the product of its perpendicular lengths. In the picture shown here, the area of this rectangle is a times b. The formula for finding the area of a rectangle is this:

Area of rectangle

Calculate area of a rectangle - example

Area of a rectangle example

So, for example if you have a rectangle of 10 inches wide by 5 inches tall. The area of that rectangle is going to be 50 inch squared.

The unit of the area is inch squared and not just inches because an area is 2 dimensional and it is the product of two one dimensional lengths, namely a and b or 5 inches and 10 inches in this case. By multiplying two one dimensional lengths together, you create a two dimensional object. Therefore, the unit of the area of this rectangle is inch squared. That's it. Now you can calculate the area of any rectangles.