Using the area of square formula to solve the problem. Then the length of the edge of the square is 9 feet.
What is a square?
It is a polygon that has four sides. The sum of the internal angle is 360 degrees. In a square, opposite sides are parallel and all sides are equal and each angle is 90 degrees. And its diagonals are also equal and intersect at the right-angle.
Given
A square has an area of 81 square feet.
We know that the area of a square is given by
[tex]\rm Area \ of \ square = (side)^2[/tex]
Then the side will be
[tex]\rm (side)^2 = Area \ of \ square\\\\(side)^2 = 81\\\\side \ \ \ \ = \sqrt{81}\\\\side \ \ \ \ = 9[/tex]
Thus, the length of the edge of the square is 9 feet.
More about the square link is given below.
https://brainly.com/question/91679
