Answer
288cm
Work Step by Step
Use the formula for the area of a rectangle.
$A=bh=64\times81=5184$
Since the area of the square is the same, use the formula for the area of a square to find the length of the square's sides.
$A=s^2$
$5184=s^2$
$\sqrt{5184}=\sqrt{s^2}$
$72=s$
Use the formula for the perimeter of a square.
$P=4s=4(72)=288$
