Positive and Negative Angles

Angles are sometimes classified based on whether their values are more than or less than 0° into positive and negative angles. The measure of a positive or a negative angle depends on the amount of rotation between the two sides forming the angle. The rotation is measured from the initial side to the terminal side of the angle.

An angle with its initial side on the x-axis is said to be in standard position.

What is a Positive Angle

An angle formed by an anti-clock wise or counterclockwise rotation from its initial side is called a positive angle.

Thus 12°, 33°, 90°, 180°, 360° are all example of positive angles.

In the given figure, let OB be the initial side of the angle. The side is then rotated by an angle θ in an anticlockwise direction such that its final side is OA. Here, ∠AOB formed is a positive angle.

What is a Negative Angle

An angle formed by a clockwise rotation from its initial side is called a negative angle.

Thus -9°, -45°, -110°, -280°, -310° are all example of negative angles.

In the given figure, the initial side is shown as OP. When this side is rotated by an angle θ in a clockwise direction, its final side is OQ. Here, ∠POQ formed is a negative angle.