[Higher only] Use y = mx + c to identify perpendicular lines.

[Higher only] Use y = mx + c to identify perpendicular lines.. Within Graphs, this learning objective sits inside Straight-line graphs for AQA Mathematics 8300. Focus on using ideas such as perpendicular accurately in your explanation. A strong response should define the core idea, describe the relevant calculation, reasoning, representation, and interpretation, and connect it back to the question wording instead of giving a vague definition. When revising, students should aim to explain the subject clearly, include precise precise mathematical notation and terminology, and show how the idea links to the wider topic rather than listing isolated facts.