The circular sector below is rolled to form a cone. Find the volume of the cone.
The slant height of the cone = 21
The circumference of the cone = (120 / 360) * 2 pi * 21 = 14 pi
The radius of the cone can be found as
14 pi = 2 pi * r
r = 7
The height of the cone = sqrt [ l^2 - r^2 ] = sqrt [21^2 - 7^2 ]
Volume of the cone is
(1/3) pi * r^2 * h =
(1/3) pi * (7)^2 * sqrt [ 21^2 - 7^2 ] ≈ 1015.94