Angles
Types of angles
An angle is an amount of turn, measured in degrees (°). We give angles different names depending on their size.
The four types
• Acute — less than 90° • Right angle — exactly 90° • Obtuse — greater than 90° but less than 180° • Reflex — greater than 180° but less than 360°
Worked examples
Acute: 60°
- 60° is less than 90°.
Answer: 60° is an acute angle.
Right angle: 90°
- 90° is exactly a quarter turn.
Answer: 90° is a right angle.
Obtuse: 135°
- 135° is more than 90° but less than 180°.
Answer: 135° is an obtuse angle.
Reflex: 300°
- 300° is greater than 180° (and less than 360°).
Answer: 300° is a reflex angle.
Where you see this in real life
- The corner of a book or a door frame is a right angle.
- The slice of a pizza that's left can be a reflex angle.
- Comparing how far a door or a pair of scissors has opened.
Key words
- Angle
- An amount of turn between two lines that meet at a point.
- Degrees (°)
- The unit of measurement for angles.
- Right angle
- An angle of exactly 90°.
- Reflex angle
- An angle that is greater than 180° and less than 360°.