Question

The length of a rectangle is five times its width. If the area of the rectangle is 320 cm^2, find its perimeter.

Answer 1

A = LW
A = 320
L = 5W

320 = W(5W)
320 = 5W^2
320/5 = W^2
64 = W^2
sqrt 64 = W
8 = W

L = 5W
L = 5(8)
L = 40

so the length (L) = 40 cm and the width (W) = 8 cm

P = 2(L + W)
P = 2(40 + 8)
P = 2(48)
P = 96  <=====