Revision Notes

What are perpendicular lines?

You should already know that PARALLEL lines have equal gradients.

PERPENDICULAR LINES do meet each other and where they do the two lines form a right angle – ie they meet at 90°.

What’s the deal with perpendicular gradients (and lines)?

Before you start trying to work with perpendicular gradients and lines, make sure you understand how to find the equation of a straight line – that will help you do the sorts of questions you will meet. 

  1. Gradients m1 and m2 are PERPENDICULAR if m1 × m2 = -1
  2. We can use m2 = -1 ÷ m2 to find a perpendicular gradient
    (This is called the NEGATIVE RECIPROCAL

If in doubt, SKETCH IT


Perpendicular Lines Example 1, IGCSE & GCSE Maths revision notes

Sketch Perpendicular Lines, IGCSE & GCSE Maths revision notes

Perpendicular Lines Example 2, IGCSE & GCSE Maths revision notes


Edexcel GCSE Maths Notes

Share with friends

Want to aim for a Level 9?

See if you’ve got what it takes. Test yourself with our topic questions.

Author: Simon

After 24 years teaching A Level Further Maths, Maths whizz Simon focused his attention on tutoring. He’s helped thousands of young people make sense of Maths and now he’s helping you too – aren’t you lucky! He’s even worked as an Edexcel examiner, so knows exactly what they’re looking for.