Answer:
13 feet
Step-by-step explanation:
Since it is a square and the perimeter is 36 feet, each side is equal to 36feet/4, 9 feet. To find the diagonal use the Pythagorean Theorem.
[tex]a^{2}+b^{2}=c^{2}[/tex]
[tex]9^{2}+9^{2}=c^{2}[/tex]
81+81=[tex]c^{2}[/tex]
162=[tex]c^{2}[/tex]
Square root both sides
c=12.728
To the nearest foot, it equals 13 feet.