The radius is the square root of the quotient of 32.1 and pi.
If I were to use 3.14 to represent pi,
32.1/ 3.14 = 10.223 (rounded to the nearest thousands)
The square root of 10.223 is 3.197 (rounded to the nearest thousands)
Thus the radius of the circle is 3.197 (rounded to the nearest thousands)