Table of Contents

## Definition

A sphere is a perfectly round geometrical object in 3D space that is the surface of a completely round ball.

## Sphere Facts

Here are some interesting facts about sphere:

- It is perfectly symmetrical
- All points on the surface are the same distance “r” from the center
- It has no edges or vertices (corners)
- It has one surface (not a face as it isn’t flat)
- It is not a polyhedron

## Volume and Surface Area

Surface Area = 4 × π × r^{2}

Volume = (4/3) × π × r^{3}

### Example

r = 21 cm

Surface Area | Volume |

Surface Area = 4 × π × r^{2}Surface Area = 4 × 22/7 × (21 cm) ^{2}Surface Area = 5544 cm ^{2} | Volume = (4/3) × π × r^{3}Volume = 4/3 × 22/7 × (21 cm) ^{3}Volume = 38808 cm ^{3} |