First, we know the formula to find the area of a square is A=s^2 where s= side length. Since we have the area, we can solve for s: 81=s^2. To solve for s, you would take the square root of both sides to get s=9. Then, we know the formula for the perimeter of a square is P=s*4. Since we now have s, we can solve for P: P=9*4 or P=36 feet which is the final answer.
The perimeter of the square would be 36 because if the side length of the square is 9 then all the other sides would be 9 as well. If you add all the sides together you get the perimeter. 9+9=18 and 18+18=36.
