EDEXCEL GCSE FOUNDATION MATHS - What are Types of Angle

Types of Angles

Angles are formed when two lines meet at a point. The point where they meet is called the vertex. We can classify angles based on their size.

1. Acute Angle

• Definition: An angle that measures less than 90 degrees.
• Symbol: ?
• Example:
• ?A = 30°
• ?B = 89°

2. Right Angle

• Definition: An angle that measures exactly 90 degrees.
• Symbol: ? with a small square at the vertex.
• Example: ?C = 90°

3. Obtuse Angle

• Definition: An angle that measures more than 90 degrees but less than 180 degrees.
• Symbol: ?
• Example:
• ?D = 100°
• ?E = 179°

4. Straight Angle

• Definition: An angle that measures exactly 180 degrees. It forms a straight line.
• Symbol: ?
• Example: ?F = 180°

5. Reflex Angle

• Definition: An angle that measures more than 180 degrees but less than 360 degrees.
• Symbol: ?
• Example: ?G = 200°

6. Full Angle

• Definition: An angle that measures exactly 360 degrees. It completes a full circle.
• Symbol: ?
• Example: ?H = 360°

Key Points to Remember:

• Angles are measured in degrees (°).
• A protractor is used to measure angles.
• The sum of angles on a straight line is 180 degrees.
• The sum of angles around a point is 360 degrees.

Example:

Here is a diagram showing different types of angles:

       A      B
    *-------*-------*
      \     /  \     /
       \   /    \   /
        \ /      \ /
         *--------*
         C        D 

?A = 30° (acute angle)
?B = 120° (obtuse angle)
?C = 90° (right angle)
?D = 180° (straight angle) 

Practice:

Identify the types of angles in the following diagram:

          A     B
      *--------*--------*
    / \      / \      / \
  /   \    /   \    /   \
 /     \  /     \  /     \
*-------*--------*--------*
     C     D      E

Answer:

• ?A = acute angle
• ?B = obtuse angle
• ?C = right angle
• ?D = obtuse angle
• ?E = straight angle