Perimeter of Rectangle


A rectangle can be explained as a 4-sided quadrilateral which contains equal opposite sides. In a rectangle, the opposite sides are always parallel to each other and commonly classified as equiangular quadrilateral. As the rectangle has no equal adjacent sides, we always get 2 different measurements. In the below image, the corners are A, B, C and D. The sides of this rectangle are AB, BC, CD and AD. Finally, the diagonals are AC and BD. 
Perimeter of a RectangleM

How to Calculate the Perimeter of a Rectangle?


Perimeter of a rectangle is nothing but the overall distance outside the rectangle as shown in the below image:
Distance Outside Rectangle


Steps to Calculate the Perimeter of a Rectangle

  1. Check the length and the width for the given rectangle
  2. By short, we'll call the length as 'l' and width as 'w'.
  3. Apply the formula, 2(l+w) or just add l + w + l + w and you've got the perimeter for the rectangle.

Perimeter of a Rectangle Problems


Problem 1: A rectangle is 6m long and 5 m wide. What is its perimeter?

Solution: Length, l = 6m.

Width, w = 5m.

Perimeter of the rectangle = 2(l+w) = 2(6+5) = 2 x 11 = 22 m.

Problem 2: A rectangle is 5cm long and its perimeter is 18cm. What is its width?

Solution: Length, l = 5cm.

Width, w say.

Perimeter of the rectangle = 18 cm.

Perimeter of the rectangle = 2(l+w)= 2l + 2w = 2(5) + 2w = 10 + 2w

Thus,   10 + 2w = 18

2w = 18 - 10 = 8 

w = 4  

Thus the width of the rectangle is 4 cm.

Problem 3: In a rectangle's length is 5x + 2 and its width is 5x - 2. If its Perimeter is 40 cm, what is the value of x?

Solution:  Length, l = 5x + 2.

Width, w = 5x - 2.

The Perimeter of the rectangle = 40 cm. ......(1)

Also by the definition of Perimeter of rectangle, 

Perimeter of rectangle = 2(l*w) = 2[(5x + 2)+(5x - 2)]  .....(2)

Equating (1) and (2),

2[(5x + 2)+(5x - 2)] = 40  

(5x + 2)+(5x - 2) = 40/2 = 20

10x = 20

x = 20/10

x = 2





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