The Perimeter of A Rectangle

Table of Contents

The perimeter of a rectangle is one of the easiest calculations that high school students will have to handle in their course. You may have heard that computing the rectangle is quite easy, and that is the fact. The perimeter of the rectangle is simply finding its entire measurement in terms of its exterior. It is not the Area of the rectangle which deals with everything about the shape.

In this piece, everything about the foundation of the shape will be discussed to give students a very good understanding of what it represents.

The Perimeter of a Rectangle Formula

The perimeter of a rectangle is simply the sum of its total plane. The formula is denoted as;

Perimeter of a Rectangle = 2 (L + W)

How to Calculate the Perimeter of a Rectangle

Step 1: Discover the length and the width

Step 2: Use the rectangle perimeter formula and compute your answer

The Rectangle

The rectangle is a shape with four sides in which the two opposite sides must be equal. The longer of the two opposite sides is known as the length, while the shorter of the two sides is the width. Below is a diagrammatical description

Example 1

It is important to know that it is only a shape with two equal lengths and two equal widths that can be identified as a rectangle. If the shape has four sides but equal lengths or unequal breadths, it is a trapezoid. Below is an example of a trapezoid

Calculating the Rectangle

Example 1

Consider the rectangle below and calculate the perimeter.


Step 1: discover the length and the width

From the shape, it is obvious that the length is 15 cm while the width is 7 cm.

Step 2: Use the rectangle perimeter formula and compute your answer

Perimeter of a rectangle = 2 (L + W)

Since L = 15 Cm, W = 7 cm

Perimeter = 2 (15 cm + 7 cm)

Perimeter = 2 (22 cm)

Perimeter = 44 cm

Example 2

Let the width of a rectangle be half of its length. Find the perimeter of the rectangle if its width is given as 3.5 cm.


From the instruction given the Width (W) = 3.5 cm

Also, the W is half the rectangle length (L) which mathematically means that;

W = ½ L

This implies;

L = 2W which subsequently means that

L = 2 (3.5 cm)

L = 7 cm

Since the length and the width have been identified, the next step will be to find the perimeter of this particular rectangle which is given as

Perimeter of a rectangle = 2 (L + W)

Since L = 7 Cm, W = 3.5 cm

Perimeter = 2 (7 cm + 3.5 cm)

Perimeter = 2 (10.5 cm)

Perimeter = 21 cm

We have considered two examples of how to find the perimeter of the rectangle, and from the computation, it is obvious that finding the answers is extremely simple. Now just like the length and the breadth were used to find the perimeter, the perimeter when made available, can also be used to find the length or width if one is missing and the other is available. The examples below will consider this

Example 3

Let the perimeter of a rectangle with a length of 13 cm by 40 cm. Find the breadth.


Since the length = 13 cm and the perimeter = 40 cm, then we only manipulate the already established parameter to find the breadth.

Perimeter of a rectangle = 2 (L + W)

40 cm = 2 (13 cm + W cm)

40 cm = 2 x 13 cm + 2 x W

40 cm = 26cm + 2W

2W = 40 cm – 26 cm

2W = 14 cm

W = 14 cm/2

W = 7 cm

So the Width is 7 cm.

This same calculation Can be used to find the length If the width and the perimeter were available.


The perimeter of the rectangle is just as easy to calculate as the perimeter of other shapes. Many things were considered in this article to explain the rectangle perimeter. The aim was to help students understand the rules that make the shape recognized as what it is, and this includes the equality of the opposite sides, which means that there is equal length and width.

Three examples were considered to fully explain how the computation work and one thing that remains consistent is that all examples were simple to compute. The last example considered how students can find the length and breadth of the shape in a situation where one of them is not available, and the perimeter is. The concept discussed here will remain consistent, and students can use it for further practice.

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