The circular sector below is rolled to form a cone. Find the volume of the cone.
The circumference of the cone = 2 * pi * 21 * (120/360) = 14 pi
The radius of the cone =
14pi = 2 * pi * r
7 = r
Height of the cone = sqrt [ 21^2 - 7^2 ] = sqrt (392) = 14sqrt 2
Volume of cone = (1/3) pi (7)^2 * 14sqrt 2 = 686sqrt (2 ) / 3 pi cm^3
+1859 
