Cambridge or Edexcel · Cambridge and Pearson Edexcel Ordinary Level (O-Level) · Mathematics · Graphs
6.3 Parallel and Perpendicular Lines
English · 5:52 · v.1 · A lesson by Teachly.lk
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About this lesson
Watch a line turn through 90° and discover why perpendicular gradients multiply to −1. Then find the equations of parallel and perpendicular lines, and where lines meet. You will learn: • Parallel lines have equal gradients • The equation of a parallel line through a point • The perpendicular rule: flip the gradient and change its sign (negative reciprocal) • The common mistake of doing only half the rule • The equation of a perpendicular line • Finding where two lines meet • Testing whether two lines are perpendicular • Practice questions with full answers This is lesson 3 of 7 in Chapter 6: Graphs 6.1 Line segments 6.2 Straight-line graphs 6.3 Parallel and perpendicular lines (this lesson) 6.4 Travel graphs 6.5 Quadratic graphs 6.6 Gradient of a curve 6.7 Graphical solutions of equations © 2026 teachly.lk. All rights reserved. This lesson and its animations are original teachly.lk content. Please do not copy, download, re-upload or share it outside teachly.lk without permission. teachly.lk is an independent learning resource and is not affiliated with Cambridge Assessment International Education.
Presented by: teachly.lk
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