# Right, Acute & Obtuse Angles

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## Basics on the topicRight, Acute & Obtuse Angles

How do we know whether an angle is acute, right, obtuse or reflex? Learn here about the different types of angles.

2 comments
2 comments
1. I'm having fun

From Kanni, 9 months ago
2. It reminds me of yoga

From Kanni, 9 months ago

## Right, Acute & Obtuse Angles exercise

Would you like to apply the knowledge you’ve learnt? You can review and practice it with the tasks for the video Right, Acute & Obtuse Angles.
• ### Identify the types of angles.

Hints

A right angle is the most common angle and forms a perfect square at the corner of the arc.

A complete circle is 360°.

An acute angle is less than 90°.

An obtuse angle is more than 90° and less than 180°.

Solution
• A straight angle or line is 180°.
• A reflex angle is more than 180° but less than 360°.
• A right angle is 90°.
• A complete angle is 360°, or a full circle.
• ### Define the terms.

Hints

Most angles have arcs.

Remember, an angle less than a right angle is an acute angle.

A vertex is where two or more lines meet.

Solution
• Obtuse angles have a large arc, more than 90° and less than 180°.
• Acute angles have a small arc less than 90°.
• The vertex is the point where two rays meet to form an angle.
• Right angles measure exactly 90°.
• ### Sort different angles.

Hints

An acute angle is less than 90°.

An obtuse angle is more than 90° and less than 180°.

Two choicies are acute angles, two choices are obtuse angles and one choice is a right angle.

Solution

OBTUSE ANGLES are more than 90° and less than 180°

• 120°
• 150°
ACUTE ANGLES are less than 90°
• 60°
• 45°
A RIGHT ANGLE is 90°

• ### Identify the types of angles.

Hints

A complete circle is 360°.

An acute angle is less than 90°.

A reflex angle is more than 180° but less than 360°.

A straight angle is also known as a line.

Solution

REFLEX ANGLES are more than 180° and less than 360°

• 215°
• 197°
ACUTE ANGLES are less than 90°
• 45°
A STRAIGHT ANGLE is 180°
A COMPLETE ANGLE is 360°, or a full circle

• ### Label the angle.

Hints

An acute angle has a small arc of less than 90°.

An obtuse angle has a large arc of more than than 90° and less than 180°.

A complete angle is 360°

Solution

A right angle is the most common angle and forms a perfect square at the corner of the arc. Its arc is 90°

• ### Name and define the angles.

Hints

This is an obtuse angle because it is greater than 90° and less than 180°.

A straight angle is also known as a line.

A complete circle is 360°.

Solution
• A right angle is 90°
• An acute angle is less than 90°
• An obtuse angle is greater than 90° and less than 180°
• A straight angle is 180°
• A reflex angle is greater than 180° and less than 360°
• A complete angle is 360°