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 10 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
💡 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
Practice questions for Parallel & Perpendicular
Which of the following is true about two parallel straight lines?
Explain why a horizontal line and a vertical line are always perpendicular to each other. Your explanation must refer to gradients.
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.