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
Some Geometric Terms and Results
Complementary and Supplementary Angles
Parallel and Transversal Lines
7th Grade Math Problems
8th Grade Math Practice
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