tzeshawn Post on Thu, 17/09/2020 2:08pm let the radius of cone be r. volume of cone = pier^2h/3 volume of pyramid = abh/3 (a,b are length and breadth of rectangle) = (12*9h)/3 = 28h (pier^2h/3)/28h = 1/3 r^2/42 = 1/3 r = sqrt(14)