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.

$Acute Angle$

∠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.

$Right Angle$

∠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.

$Obtuse Angle$

∠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.

$Straight Angle$

∠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.

$Reflex Angle$

∠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.