Perimeter of a Rectangle – Definition with Examples

Home » Perimeter of a Rectangle – Definition with Examples

Perimeter of Rectangle

The perimeter of a two-dimensional shape is the total length of the outline. To find the perimeter of a rectangle, we add the lengths of all four sides. Since opposite sides of a rectangle are always equal, we need to find the dimensions of length and width to find the perimeter of a rectangle. We can write the perimeter of the rectangle as twice the sum of its length and width. The perimeter is a linear measure and has units as meters, centimeters, inches, feet, etc.

Formula for the Perimeter of a Rectangle

formula for the Perimeter of a Rectangle - SplashLearn

The letter ‘P’ denotes the perimeter of a rectangle. Let l denote the length and w denote the width of the rectangle. The perimeter (P) of a rectangle is the total length of all the sides of the rectangle. Since the opposite sides of a rectangle are equal, a rectangle has two equal lengths and two equal widths.

The formula for the perimeter of a rectangle is given below:

Perimeter = length + length + width + width

P = l + l + w + w

Or, P = 2 (l + w)

Hence, the formula for the perimeter of a rectangle, P = 2 × (length + width) = 2 × (sum of adjacent sides)

Real-World Applications

  • To find out the distance covered by walking around a rectangular park.
  • To measure the length of barbed wire required to create a fence around a rectangular plot of land.
  • To draw a border with limestone around a rectangular ground and determine how much limestone would be required to mark the ground’s total periphery. 

Solved Examples

  1. The length of a rectangle is 25 cm and the width is 4 cm. What is the perimeter of this rectangle?

Solution:

Length of the rectangle, l = 25 cm

Width of the rectangle, w = 4 cm

Perimeter of the rectangle, P = 2 (l + w) = 2 (25 + 4) = 58

The perimeter of the given rectangle is 58 cm.

  1. The length of a rectangular yard is 10 m more than the width. If the yard’s length is 25 m, find the perimeter of this rectangular yard?

Solution:

The length of the rectangular yard is 10 m more than the width. Since the length of the yard is 25 m, the width of this rectangular yard is 25 m – 10 m or 15 m.

Length of the yard, l = 25 m

Width of the yard, w = 15 m

Perimeter, P = 2 (l + w) = 2 (25 + 15) = 2 (40) = 80

The perimeter of the given rectangle is 80 m.

  1. The perimeter of a rectangle is 100 cm. The length of this rectangle is 35 cm. Calculate the width of the rectangle.

Solution:

Using the formula P = 2 (l + w), we can say that 2 (35 + w) = 100

Or, 35 + w = 1002  = 50

Therefore w = 50 – 35 = 15

The width of the given rectangle is 15 cm.

Practice Problems

Perimeter Of A Rectangle

Attend this Quiz & Test your knowledge.

1The perimeter of a rectangle is 150 cm, and the width is 20 cm. What is the length of this rectangle?

40 cm
45 cm
50 cm
55 cm
CorrectIncorrect
Correct answer is: 55 cm
150 = 2 (l + 20). Hence, l + 20 = 150 ÷ 2 = 75, or l = 75 - 20 = 55 cm.

2The length and width of a rectangle are 35 cm and 25 cm, respectively. What is the perimeter of this rectangle?

100 cm
110 cm
115 cm
120 cm
CorrectIncorrect
Correct answer is: 120 cm
P = 2(35+25) = 2(60) = 120 cm

3The length of a rectangle is twice its width. If the width of a rectangle is 45 cm, calculate the perimeter of the rectangle.

135 cm
170 cm
200 cm
270 cm
CorrectIncorrect
Correct answer is: 270 cm
Length = 2(width) = 2(45) = 90 cm. So, P = 2(90 + 45) = 2(135) = 270 cm.

4The perimeter of a rectangle is 250 cm. The length of the rectangle is 1/5th of the perimeter. What is the width of the rectangle?

60 cm
75 cm
100 cm
150 cm
CorrectIncorrect
Correct answer is: 75 cm
Length = ⅕ (250) = 50 cm. Now, P = 2 (50 + w) = 250. So, w = $\frac{250}{2}$ – 50 = 75 cm


Frequently Asked Questions

The perimeter measures the length of the boundary of the rectangle. It is given by the sum of all sides of the rectangle and expressed in linear units. Area, on the other hand, measures the space within the rectangle. It is the product of the length and width of the rectangle and is expressed in square units. 

Since the perimeter of a rectangle is the total distance covered by its boundaries or the sides, the unit of the perimeter (as distance) can be centimeters, meters, feet, yards, etc.

 - SplashLearn

Source
Yes. The perimeter of Rectangle A is 20 cm. The perimeter of Rectangle B is 20 cm. As the sides differ, so do their areas. The area of Rectangle A is 16 cm2, while the area of Rectangle B is 24 cm2.

Perimeter of Rectangle = 2 (Length + Width). Rearranging the terms in this formula, we get, Length = $\frac{Perimeter}{2}$ – Width. So, to find the length of a rectangle, subtract the width from half of the perimeter.


Perimeter of a Rectangle – Definition with Examples

Shapes

Play Now
Perimeter of a Rectangle – Definition with Examples

Angles

Play Now
Perimeter of a Rectangle – Definition with Examples

Parallel and Perpendicular Lines

Play Now