Explanation:
Let length is x and breadth is y.
The formula for the area and the perimeter of a rectangle is given by :
A = xy
P = 2(x+y)
Here, A = 8 mi² and P = 16 miles
Putting all the values,
xy = 8
y=8/x ......(1)
2(x+y) = 16
x+y = 8 .....(2)
Put equation (2) in equation (1) as follows :

When we solve, we get :
x = 6.82 miles, 1.17 miles
Put the value of x in equation (1)
When x = 6.82 miles,
y = 8/6.82
y = 1.17 miles
When x = 1.17 miles,
y = 8/1.17
y = 6.82 miles
Hence, the dimension of the field is 6.82 miles and 1.17 miles.