Question

Suppose a sphere, cylinder, and cone all share the same radius. The cylinder and cone also share the same height, which is twice the radius. Which of the following is true about the relationship between the volume formulas for the sphere, cylinder, and cone?

A. Sphere = Cylinder + Cone
B. 3 Cones = 1 Cylinder
C. Sphere - cone = Cylinder
D. 1 Cylinder + 2 cones + 1 Sphere

Answer 1

Compute with radius r and height h = 2r.

- Sphere: V = (4/3)πr^3.
- Cylinder: V = πr^2·(2r) = 2πr^3.
- Cone: V = (1/3)πr^2·(2r) = (2/3)πr^3.

Therefore 3·(cone) = 3·(2/3)πr^3 = 2πr^3 = (cylinder). So B is correct.