Find perimenter ot rectangle

Question

A rectangle is 4 times as long as it is wide. If the area is 36 square feet, find the perimenter.

Answer 1

Let L = Length and W = width.

Perimeter = 2(L + W)

L = 4W

 

Substitute 36 = 2(4W +W) => 18 = 5W => W = 18/5 and L = 72/5

You should check to see that these answers satisfy the original problem.

 

Answer 2

P = 2l + 2w

 

A = lw

 

l = 4w

 

A = 36 = (4w)w = 4 w^2

 

36 = 4w^2

 

9 = w^2

 

w = √9

 

l = 4√9

 

P = 2l + 2w

 

P = 2(4√9) + 2(√9)

 

P = 8√9 + 2√9 = 10√9