Question

The length of a rectangle is four times its width. if the area of the rectangle is 100 cm2 , find its perimeter.

Answer 1

Define x:
Let the width be x.
width = x
Length = 4x

Given the area, find Length and Width:
The area is 100 cm²

Area = Length x Width
x(4x) = 100

Evaluate the Left Hand Side:
4x² = 100

Divide by 4:
x² = 25

Square root both sides:
x = 5

Find the Width and the Length:
Width = x = 5
Length = 4x = 4(5) = 20

Find Perimeter:
Perimeter = 2( 5 + 20) = 50 m

Answer: Perimeter = 50 m