GCSEMaths: FoundationEdexcelRevision NotesGeometry & MeasuresAngles in Polygons & Parallel LinesBasic Angle Properties

Basic Angle Properties (Edexcel GCSE Maths: Foundation)

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Jamie W

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Jamie W

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Basic Angle Properties

What are the basic angle properties?

  • Angles around a point add up to 360°
  • Angles that form a straight line add up to 180°
  • Vertically opposite angles are equal
    • Vertically opposite angles occur when two lines intersect, as in the diagram below

Vertically opposite angles

Examiner Tip

  • Use the angle properties to find any missing angles that you can, and mark them on the diagram
    • Even if they are not the angle you are trying to find, they may help provide a clue!

Worked example

The diagram below shows three straight lines intersecting at a point.

Basic angle properties worked example questionFind the values of x and y.

Vertically opposite angles between two intersecting lines are equal

x space equals space 25

Angles that meet on a straight line add up to 180°

table row cell x space plus space y space plus space 98 space end cell equals cell space 180 space end cell row cell 25 space plus space y space plus space 98 space end cell equals cell space 180 end cell row cell 123 space plus space y space end cell equals cell space 180 end cell end table

Solve to find y

table row cell y space end cell equals cell space 180 space minus space 123 space end cell row cell y space end cell equals cell space 57 end cell end table

bold italic x bold space bold equals bold space bold 25 bold space bold comma bold space bold italic y bold space bold equals bold space bold 57

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    Jamie W

    Author: Jamie W

    Expertise: Maths

    Jamie graduated in 2014 from the University of Bristol with a degree in Electronic and Communications Engineering. He has worked as a teacher for 8 years, in secondary schools and in further education; teaching GCSE and A Level. He is passionate about helping students fulfil their potential through easy-to-use resources and high-quality questions and solutions.