Parallel & Perpendicular Gradients (Edexcel A Level Maths: Pure)

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Parallel & Perpendicular Gradients

What are parallel lines?

Parallel & Perpendicular Gradients Notes Diagram 1, A Level & AS Level Pure Maths Revision Notes

  • Parallel lines are equidistant meaning they never meet
  • Parallel lines have equal gradients

Parallel & Perpendicular Gradients Notes Diagram 2, A Level & AS Level Pure Maths Revision Notes 

What are perpendicular lines?

Parallel & Perpendicular Gradients Notes Diagram 3, A Level & AS Level Pure Maths Revision Notes

  • Perpendicular lines meet at right angles
  • The product of their gradients is -1

Parallel & Perpendicular Gradients Notes Diagram 4, A Level & AS Level Pure Maths Revision Notes 

What are collinear lines?

  • Collinear lines are two line segments that are part of the same line
  • They have equal gradients and pass through, or meet at, a point
  • Rearrange their equations into the same form and they will be identical

Parallel & Perpendicular Gradients Notes Diagram 5, A Level & AS Level Pure Maths Revision Notes

How do I tell if lines are parallel or perpendicular?

  • Rearrange equations into the form y = mx + c
  • m is the gradient

Parallel & Perpendicular Gradients Notes Diagram 6, A Level & AS Level Pure Maths Revision Notes

Examiner Tip

  • Exam questions are good at “hiding” parallel and perpendicular lines.
  • For example a tangent and a radius are perpendicular.
  • Parallel lines could be implied by phrases like “… at the same rate …”

Worked example

Parallel & Perpendicular Gradients Example Diagram, A Level & AS Level Pure Maths Revision Notes

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Paul

Author: Paul

Expertise: Maths

Paul has taught mathematics for 20 years and has been an examiner for Edexcel for over a decade. GCSE, A level, pure, mechanics, statistics, discrete – if it’s in a Maths exam, Paul will know about it. Paul is a passionate fan of clear and colourful notes with fascinating diagrams – one of the many reasons he is excited to be a member of the SME team.