The length of a rectangle is twice its width.
If the area of the rectangle is 72 , find its perimeter.

Question

The length of a rectangle is twice its width. 
If the area of the rectangle is 72  , find its perimeter.

anonymous · Answer

To get started, relate the length and width. We know that the length is twice the width so
 
l = 2w
 
We know the area is 72, so we use the area formula for a rectangle:
 
lw = 2w(w) = 2w2 =72
 
Solving for w:
 
2w2 = 72
w2 = 36
w = 6
 
The length equals
 
l = 2w
l = 12
 
and the dimensions are 6 x 12
 
The perimeter is the sum of the lengths of all four sides or
 
2w + 2l = 2(6) + 2(12) = 36

shane_b · Answer

$$A=LW=72$$You need to find L and W to get the perimeter since $$P=2L+2W$$To find L and W, rewrite the area equation in terms of one variable knowing that L=2W:$$A=(2W)W$$You should see that W= 6.  Now you can use the area equation to solve for L.  Once you have L and W, you can find the perimeter quite easily.