What is a angle?

An angle measures how much one line has turned from another where they meet (the vertex). Angles are measured in degrees (°). A right angle is 90°, a straight line is 180°, and a full turn is 360°.

Examples

• A right angle is exactly 90°.
• An acute angle is less than 90°.
• An obtuse angle is between 90° and 180°.

Quick facts

• The corner of a square or a book is a right angle (90°).
• Angles on a straight line add up to 180°.