Formation of angle by Rotation

The amount of rotation of a line from its initial position to final position is called an angle formed by rotation.

Example

A straight line can make an angle geometrically by moving from its initial position to final position.

$\overrightarrow{RS}$ is a ray and it is rotated to new position, where it is called as $\overrightarrow{RT}$. The amount of rotation of line $\overrightarrow{RS}$ to become $\overrightarrow{RT}$ is called an angle.

An angle is formed between lines $\overrightarrow{RS}$ and $\overrightarrow{RT}$ by the rotation and it is denoted by $\angle SRT$ or $\angle TRS$ in mathematics.