What is the relation between the radius of curvature and the focal length of a mirror?

Relation between the radius of curvature and the focal length of a mirror:

1. Radius of curvature is the radius of the sphere of which the spherical mirror forms a part. It is denoted by "$\text{R}$“.
2. Thus, the length between the pole ($\text{P}$) of a mirror and the principal focus ($\text{F}$) is called focal length ($\text{f}$).
3. The radius of curvature of the spherical mirror is twice the focal length ($\text{f}$).

$\text{R}$$=2\text{f}$

Here, $\text{R}$ is the radius of curvature and $\text{f}$ is the focal length of a mirror.