Edexcel IGCSE Maths

Revision Notes

4.6.2 Circle Theorems - Tangents

What do I need to know about tangents

1. A radius and a tangent are perpendicular

Radius tangent 90, IGCSE & GCSE Maths revision notes

  • Note that perpendicular lines meet at right angles

2. Not strictly a circle theorem but a very important fact for solving some problems

Equal length tangents, IGCSE & GCSE Maths revision notes

  • In this sense the tangents end at two points – the first point is where the two tangents meet and the other end is where each one touches the circle
  • Notice because of the circle theorem above that the quadrilateral ROST is a kite with two right angles

Exam Tip

Add anything you can to a diagram you have been given – write in any angles and lengths you can work out, even if they don’t seem relevant to the actual question.

Also, when asked to “give reasons” (this is very common), aim to quote an angle fact or circle theorem for every angle you find, not just one for the final answer.

Likewise, for each angle you work out, try to assign an angle fact or circle theorem to it – giving the names/titles/phrases for each of these is exactly what the examiners want to see.

Worked Example

Circle Theorems - Tangents Worked Example 1, downloadable IGCSE & GCSE Maths revision notes

 

Q1a Circle Theorems 1, IGCSE & GCSE Maths revision notes

Circle Theorems - Tangents Worked Example 2, downloadable IGCSE & GCSE Maths revision notes

Q1a Circle Theorems 2, IGCSE & GCSE Maths revision notes

Circle Theorems - Tangents Worked Example 3, downloadable IGCSE & GCSE Maths revision notes

Circle Theorems - Tangents Worked Example 4, downloadable IGCSE & GCSE Maths revision notes

Q1b Circle Theorems 2, IGCSE & GCSE Maths revision notes

Circle Theorems - Tangents Worked Example 5, downloadable IGCSE & GCSE Maths revision notes

Close

Join Save My Exams

Download all our Revision Notes as PDFs

Try a Free Sample of our revision notes as a printable PDF.

Join Now