Without any more information we can't find the actual numerical representation of the length and width but we can give an expression that will allow us to find them...
We let the width equal x, so the length is 3x. That would be the dimensions...
length = 3x
width = x
So to find perimeter the expression would be
2(3x) + 2(x) =
6x + 2x =
8x
For the area it would be
a= length × width
a = 3x × x
a = 3x^2
Consider two points in a two dimensional coordinate plane

As you know mid point of a line joining two points is the coordinate of the middle point of only that portion of line joining between two points.
[tex]\text { Mid point of } (x_{1},y_{1})\text { and } (x_{2},y_{2}) =(\frac{x_{1}+x_{2}}{2} ,\frac{y_{1}+y_{2}}{2})[/tex]
As we know distance formula gives the Distance between line joining two points in two dimensional coordinate system.It is always positive.
[tex]\text { Distance formula between two points } (x_{1},y_{1})\text { and } (x_{2},y_{2}) =\sqrt{(x_{2}-x_{1})^2+(y_{2}-y_{1})^2}[/tex]
Distance formula gives the distance between two points, whereas Mid point formula gives coordinate of the middle point.
Answer:
11.4
Step-by-step explanation:
Distance Formula: 
1. 
2. 
3. 
4. 
5. 
6. 
P = 2l + 2w
l = 2x
w = x
66 = 2(2x) + 2(x)
66 = 4x + 2x
66 = 6x
/6 /6
11 = x
L = 2x
L = 2(11)
L = 22
W = x
W = 11
Therefore the length is 22ft and the width is 11ft