A = a^2.....where " a " is the size of 1 side A = 256
256 = a^2...take sqrt of both sides, eliminating the ^2 sqrt 256 = a 16 = a
so each side is 16 ft....now we find the perimeter P = 4a....where " a " is the size of each side P = 4(16) P = 64.......so they will need 64 ft of fencing <===