Question

A piece of paper in the form of a sector of a circle of radius 15 cm is rolled into a cone. Calculate the volume of the cone if the angle of the sector is 240 degrees.

Answer 1

Since s=rθ, the circumference of the base of the cone is

15 * 4π/3 = 20π

So, the radius of the base of the cone is 10.

Now you can find the height of the cone, and thus the volume.