Answer:
6 miles
Explanation:
Let's say the length of the sides of the square is x.
The area of a square is denoted by: A = x².
Here, we're given that twice the area of the square is 72, so we can write this is 2 times the area, which is 2 * x². Set this equal to 72 and solve:
2x² = 72
x² = 36
x = 6
Thus the answer is 6 miles.