The length of a rectangle is twice its width. If the perimeter of the rectangle is 42 in, find its length and width.

Answer 1

Start with the formula for the perimeter of a rectangle:

2L + 2W = 42

Since the length is twice the width, you also know the following:

L = 2W

Substitute this in for L in the perimeter equation and you get the following:

2*2W + 2W = 42

4W + 2W = 42

6W = 42

W = 7

Since L = 2W

L = 2*7

L = 14