The perimeter of a rectangle equals the sum of the lengths of its four sides. If the width of a rectangle is 7 inches and its preimeter is 42 inches, find the length of the rectangle.

The length of the rectangle is __ inches

I know the formula is P=2L+ 2W but the length is needed do I use the same formula?

Question

The perimeter of a rectangle equals the sum of the lengths of its four sides. If the width of a  rectangle is 7 inches and its preimeter is 42 inches, find the length of the rectangle.

The length of the rectangle is __ inches

I know the formula is P=2L+ 2W but the length is needed do I use the same formula?

anonymous · Answer

P = 2L + 2W
42 = 2L + 2(7)
42 = 2L + 14
42 - 14 = 2L
28 = 2L
28/2 = L
14 = L

check....
P = 2L + 2W
42 = 2(14) + 2(7)
42 = 28 + 14
42 = 42 (correct)

mathstudent55 · Answer

You have perimeter = P = 42 in.
width = W = 7 in.
The only unknown is the length, L
Use the formula you have, and replace P and W with the known numbers. Then solve for L, the length.