The radius of circle is 6.5 centimetres. asquare has the same are as this circle. the length of each side of square , in centimetre is?

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)