In other words, an angle measuring between 0° to 90° is called an acute angle. ∠ABCin the given figure is an acute angle.

You are watching: An angle that measures between 90 and 180 degrees ∠MON shown in adjoining figure is equal to 60°. So, ∠MON is an acute angle.

2. Right Angle:

An angle whose measure is 90° is called right angle.

In other words, an angle which measure exactly 90° is called a right angle.

Twolines that meet at a right angle are called perpendicular lines. In the above figure, ∠AOB is a right angle. In this case,we say that the arms OA and OB are perpendicular to each.

Therefore, ∠AOB shown in adjoining figure is 90°. So, ∠AOB is a right angle.

3. Obtuse Angle:

An angle whose measure is greater than 90° but less than 180° is called an obtuse angle.

In other words, an angle measuring between 90° to 180° is called an obtuseangle. ∠DOQ shown in the above figure is an obtuse angle.

4. Straight Angle:

An angle whose measure is 180° is called a straight angle.

In other words, an angle which measures exactly 180° is called a straightangle. ∠XOY shown in the above figure is a straight angle. A straight angle is equal to two right angles.

5. Reflex Angle:

An angle whose measure is more than 180° but less than 360° is called a reflex angle. ∠AOB shown in the above figure is 210°. So, ∠AOB is a reflex angle.

6. Zero Angle:

An angle measure 0° is called a zero angle.

When two arms of an angle lie on each other, 0° angle is formed.

Comparision of Angles

An angle whose degree measure is greater than the degreemeasure of another angle is a greater angle. Thus, we can say that:

Acute Angle Questions and Answers on Types of Angles:

I. Classify the given angles as acute, obtuse, right andstraight.

(i) 158°

(ii) 90°

(iii) 36°

(iv) 180°

(v) 91°

(i) Obtuse Angle

(ii) Right Angle

(iii) Acute Angle

(iv) Straight Angle

(v) Obtuse Angle

Angle.

Interior and Exterior of an Angle.

Measuring an Angle by a Protractor.

Types of Angles.

Pairs of Angles.

Bisecting an angle.

Construction of Angles by using Compass.

Worksheet on Angles.

Geometry Practice Test on angles.