Positive angle

Definition

The amount of rotation of a ray from its initial position to final position in anticlockwise direction is called positive angle.

Anticlockwise direction is considered as positive direction in the case of angle. There is a universally accepted reason to consider anticlockwise direction as positive direction. Every book is opened in anticlockwise direction and we feel positively to start reading or writing. So, the anticlockwise direction is considered as positive direction in the case of angle.

Positive angles are written by writing with or without plus sign $(+)$ before the angle.

Example

$\overrightarrow{MN}$ is a ray and it is initially at a position on the plane.

The ray $\overrightarrow{MN}$ is rotated in anticlockwise direction and reached its final position where it is known as ray $\overrightarrow{MO}$.

The direction of angle made by the ray is anticlockwise direction and it is considered as positive direction.

Hence, the angle made by the ray $\overrightarrow{MN}$ to become $\overrightarrow{MO}$ is known as positive angle.

For example, if angle is $30^°$ and it is made in anticlockwise direction, it is written as $30^°$ or $+30^°$ in mathematics.

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