The perimeter of the square is 36 cm.
Step-by-step explanation:
We know that a square has all equal sides, and that the formula for area is Length x width. uWith that knowledge, we find the square root of 81, which is 9. Now we know that the lengths of the square are all 9 cm. Since the formula for perimeter is length + width + length + width, 9 + 9 + 9 + 9 = 36. Therefore, the perimeter of the square is 36cm