The formula for the Circumference of a circle is 2 x 3.14 (Pi) x R (or 3.14D).
Our current equation gives us C = 6Pi. This means that we have the diameter.
6 must be our diameter, as we already have Pi.
Since our formula states that we need 2 x R to make D, we must divide the diameter by 2 to get R.
6 / 2 = 3.
Your radius is 3in.
I hope this helps!