Angles

• An angle is the amount of turn between two lines. Angles are measured in degrees and denoted by the symbol °.

• Angles can be sorted into types depending on their size. These are:

  • acute angles
  • right angles
  • obtuse angles
  • reflex angles.

• When working out the size of missing angles it is important to recall and use the angles rules for vertically opposite angles, angles on a straight line, angles at a point, angles in triangles and angles in quadrilaterals.

Make sure you are confident with solving linear equations before working with angles written as algebraic expressions.

• Angles are based on fractions of a full turn or 360°.

  • An acute angle is less then 90°.
  • A quarter turn, which measures 90°, is called a right angle.
  • An obtuse angle is between 90° and 180°.
  • A reflex angle is between 180° and 360°.

• Angles can be indicated by 3 letters, representing each point that make up an angle. The middle letter shows the point around which the angle is situated, eg ABC indicates an angle around point B.

• Line segments can be named or labelled with two letters (eg EF) and describe the starting and finishing points of the line.

Find out more about the different angles below

To work out the size of opposite angles, angles on a straight line and at a point, there are some important rules to remember.

Find out more, along with a worked example

To work out the size of interior angles, there are some important rules to remember.

Find out more, along with a worked example

Practise what you've learned about angles with this quiz.

Now you've revised angles, why not take a look at area?