The length of a rectangle is twice the width. Find the length of the rectangle if the perimeter is 42cm.

Answer: The length of the rectangle is 14 cm

Step-by-step explanation: The information given is such that the length is twice the width, so if the width is W, then the length is 2W. Also the question states that the perimeter is 42 cm. The perimeter of a rectangle is derived as

Perimeter = 2 (L + W)

If the length is 2W and the width is W, we can now express the perimeter as,

42 = 2 (L + W)

42 = 2 (2W + W)

42 = 2 (3W)

42 = 6W

Divide both sides of the equation by 6

W = 7

If the width is 7, and the length is twice the width l, then the length is now 2 x 7 = 14

Therefore the length of the rectangle equals 14 cm.