# Classification of Angles

Classification of angles on the basis of their degree measures are given below:

Acute Angle:

An angle whose measure is more than 0° but less than 90° is called an acute angle. Angles having magnitudes 30°, 40°, 60° are all acute angles. In the adjoining figure, ∠X0Y represents an acute angle.

∠X0Y < 90°

Right Angle:

An angle whose measure is equal to 90° is called a right angle. In the adjoining figure ∠ABC represents a right angle.

∠ABC = 90°

Obtuse Angle:

An angle whose measure is more than 90° but less than 180° is called an obtuse angle. In the adjoining figure, ∠XYZ represents an obtuse angle.

∠XYZ > 90°

∠XYZ < 180°

Straight Angle:

An angle whose measure is equal to 180° is called a straight angle. In the adjoining figure, ∠XOY represents a straight angle.

∠XOY = 180°

Reflex Angle:

An angle whose measure is more than 180° but less than 360° is called a reflex angle. In the adjoining figure, ∠POQ is a reflex angle. Angles having magnitudes 220°, 250°, 310° are all reflex angles.

∠POQ > 180°

∠POQ < 360°

Complete Angle:

An angle whose measure is equal to 360° is called a complete angle. In the adjoining figure, ∠BOA represents a complete angle.

60 minutes = 1 revolution = 1 complete angle.

These are the adjoining figures of the classification of angles on the basis of their degree measures.

Lines and Angles

Fundamental Geometrical Concepts

Angles

Classification of Angles

Related Angles

Some Geometric Terms and Results

Complementary Angles

Supplementary Angles

Complementary and Supplementary Angles

Linear Pair of Angles

Vertically Opposite Angles

Parallel Lines

Transversal Line

Parallel and Transversal Lines