## Definition

The distance from centre of the circle to any point on the circumference of the circle is called radius of the circle.

Radius is a distance between centre of the circle and any point on the circumference of the circle.

The radius of the circle is symbolically represented by a line segment that joins the centre of the circle and any point on the circumference of the circle.

The length of the line segment is also known as its radius. The radius of any circle is usually denoted by the letter $r$ in mathematics.

### Example

$C$ is centre of the circle and $D$ is any point on the circumference of the circle.

The distance from point $C$ to point $D$ is known as radius of this circle and it seems as the length of the line segment $\overline{CD}$.

Radius ($r$) $= CD$