GraphsDeep Dive
Finding Parallel and Perpendicular Lines
Part of Parallel & Perpendicular — GCSE Mathematics
This deep dive covers Finding Parallel and 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 6 of 9 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 6 of 9
Practice
14 questions
Recall
12 flashcards
Finding Parallel and Perpendicular Lines
To find a parallel line:
- Find the gradient of the original line
- Use the same gradient for the new line
- Use given point to find the y-intercept
- Write equation in form y = mx + c
To find a perpendicular line:
- Find the gradient of the original line
- Calculate the perpendicular gradient: -1/m
- Use given point to find the y-intercept
- Write equation in form y = mx + c
Special Cases
| Original Line | Parallel Line | Perpendicular Line |
|---|---|---|
| Horizontal (m = 0) | Also horizontal | Vertical (x = constant) |
| Vertical (undefined m) | Also vertical | Horizontal (y = constant) |
| m = 1 | m = 1 | m = -1 |
| m = 2 | m = 2 | m = -1/2 |