Question

The length of a rectangle is five times its width.

If the area of the rectangle is 405cm^2, find perimeter

Answer 1

108

Explanation:

Let's say the width is x

Of the length is 5 times the width, then the length is 5x

Area = length * width

405 = x * 5x

405 = 5x^2

405/5 = 5x^2/5

81 = x^2

Take the square root of both sides

2/[81 = 2/[x^2

9 = x = width

9 × 5 = 45 = length

Perimeter = 2 × length + 2 × width

2 × 45 + 2 × 9

90 + 18 = 108