The volume of a cone with a height of 6 cm is 8 pi cubic centimeters. Which expression can be used to find r, the radius of the base of the cone? 6 = one-third pi (r squared) (8 pi) 8 pi = one-third pi (r) (6 squared) 6 = one-third (pi r)(8 pi) 8 pi = one-third pi (r squared) (6)