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Exam Tips for Parallel & Perpendicular Lines

Part of Parallel & Perpendicular — GCSE Mathematics

This exam tips covers Exam Tips for Parallel & Perpendicular Lines within Parallel & Perpendicular for GCSE Mathematics. Revise Parallel & Perpendicular in Graphs for GCSE Mathematics with 14 exam-style questions and 12 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 8 of 9 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.

Topic position

Section 8 of 9

Practice

14 questions

Recall

12 flashcards

💡 Exam Tips for Parallel & Perpendicular Lines

  • Check your arithmetic: Be careful with negative signs when finding perpendicular gradients
  • Remember the rule: Parallel = same gradient, Perpendicular = gradients multiply to -1
  • Use fractions: Keep perpendicular gradients as fractions for accuracy
  • Verify your answer: Substitute the given point into your final equation
  • Special cases: Remember horizontal and vertical lines are always perpendicular
  • Show working: Always show how you found the gradient relationship

Keep building this topic

Read this section alongside the surrounding pages in Parallel & Perpendicular. That gives you the full topic sequence instead of a single isolated revision point.

Worked ExamplesReal-World ApplicationsTrain Tracks and Right AnglesParallel Lines

Practice Questions for Parallel & Perpendicular

Which of the following is true about two parallel straight lines?

  • A. They have the same gradient but different y-intercepts
  • B. Their gradients multiply to give -1
  • C. They have the same gradient and the same y-intercept
  • D. One gradient is the negative of the other
1 markfoundation

Explain why a horizontal line and a vertical line are always perpendicular to each other. Your explanation must refer to gradients.

2 marksstandard

Quick Recall Flashcards

What is the gradient rule for perpendicular lines?
Perpendicular lines have gradients that multiply to -1. If L1 perp L2 then m1 x m2 = -1.
What is the gradient rule for parallel lines?
Parallel lines have equal gradients. If L1 has gradient m1 and L2 has gradient m2, then L1 || L2 means m1 = m2.

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