In the circle, segment AB is a diameter. If the length of arc ACB is 6pi, what is the length if the radius of the circle?

Arc   ACB would be 1/2 of the circle

          the WHOLE circle would be   pi x diameter = ABpi

             so 1/2 of ABpi = 6pi

                        1/2 ABpi = 6pi

                              AB =12         this is the diameter..... radius would be  6 units