The circular sector below is rolled to form a cone. Find the volume of the cone.
l = 21 cm
Circumference of cone = (120/360)* 2pi (21) = 14 pi cm
Radius of cone = 14 pi / 2pi = 7 cm = r
Volume of cone = (1/3) pi r^2 * [sqrt ( l^2 - r^2 ) ] =
(1/3) pi (7^2) * [ sqrt ( 21^2 - 7^2) ] ≈ 1015.94 cm^2
+1418 
