GCSE MATHS • HIGHER TIER
Stretches Made Simple
Stretch points, shapes and graphs accurately in one direction using scale factors.
Clear method
Exam practice
Worked proofs
Stretches in Four Moves
1
Identify
Identify whether the stretch is horizontal or vertical.
2
Find
Find the scale factor and determine which coordinate will change.
3
Multiply
Multiply only the affected coordinate by the scale factor.
4
Check
Keep the unaffected coordinate unchanged and check the transformed result.
What You’ll Learn
Understand what a stretch is.
Understand how stretches differ from enlargements.
Use scale factors correctly.
Apply vertical stretches to coordinates.
Apply horizontal stretches to coordinates.
Stretch complete shapes vertex by vertex.
Understand stretches of graphs.
Key Rules
Vertical stretch
Change the y-coordinate only. Keep the x-coordinate unchanged.
(x,y)→(x,ky)
Horizontal stretch
Change the x-coordinate only. Keep the y-coordinate unchanged.
(x,y)→(kx,y)
Worked Proof: Stretches
Step-by-Step Method
- 1. Identify whether the stretch is horizontal or vertical.
- 2. Find the scale factor and decide which coordinate will change.
- 3. Multiply only the affected coordinate by the scale factor.
- 4. Keep the unaffected coordinate unchanged and check the new coordinates.
More Worked Examples
1
Stretch the point (3, 4) vertically by scale factor 2.
Step 1 : Keep the x-coordinate.
Step 2: Multiply the y-coordinate by 2. 4 × 2 = 8
2
Stretch the point (5, 2) vertically by scale factor 3.
Step 1 : Keep the x-coordinate.
2 × 3 = 6
3
Stretch the point (4, 3) horizontally by scale factor 2.
Step 1 : Double the x-coordinate.
Step 2: Keep the y-coordinate.
y = 3
4
Stretch the point (2, 7) horizontally by scale factor 3.
Step 1: Multiply the x-coordinate by 3.
Step 2: Keep the y-coordinate.
y = 7
- Common GCSE Mistakes
- Changing both coordinates.
- Applying the wrong scale factor.
- Confusing stretches with enlargements.
- Forgetting which coordinate changes.
- Arithmetic errors when multiplying coordinates.
- Exam Tips
- Identify whether the stretch is horizontal or vertical first.
- Vertical stretch: change y only.
- Horizontal stretch: change x only.
- Write down the scale factor before transforming coordinates.
- Keep the unaffected coordinate unchanged.
- Transform every vertex separately when stretching a shape.
Skills Used in Stretches
Stretches
Scale Factors
Coordinates
Vertical Transformations
Horizontal Transformations
Graph Transformations
Ready to Practise?
Watch the Stretches Tutorial
Step-by-step walkthroughs of Stretches with clear methods and exam tips.
Frequently Asked Questions
A stretch changes the size of a shape in one direction only.
An enlargement changes dimensions proportionally, while a stretch affects only one direction.
The y-coordinate changes according to the scale factor while the x-coordinate stays unchanged.
The x-coordinate changes according to the scale factor while the y-coordinate stays unchanged.
It halves distances in the stretched direction.
Apply the stretch to every vertex separately, then join the transformed points.