Since the square has the same area as the circle, it might help
if we look at the area of the circle first.
The area of any circle is Area = (pi) x (radius)² .
Leave it in that form for just a second . (Oh, this is going to be so easy . . .)
The area of a square is (length of a side)² .
The problem says that the areas are equal. So . . .
(length of each side)² = (pi) x (radius)²
Take the square root of each side of the equation:
Length of each side of the square = (radius of the circle) times ( √pi )
Length of each side = (6.5 centimeters) times ( √pi ) = 11.52 centimeters (rounded)