sphere

A sphere is a three-dimensional shape with a circular face. It has no vertices or sides. Every point on the surface of a sphere is equidistant from the centre of the sphere.

The formula for the volume of a sphere is:

\text {Volume} = \dfrac{\text{4}} {\text{3}} \times \pi \times {r^{3}}

                = \dfrac{\text{4}}{\text{3}}\pi {r^{3}}

In this formula r represents the radius of a sphere. This is the distance from the centre of the sphere to any point on the surface of the sphere.

The formula for the surface area of a sphere is:
\textmd {Surface area} = \textmd {4}\times\pi\times {r^{2}}
                         = \textmd {4}\pi {r^{2}}
Snooker balls are examples of congruent spheres.