Transformations

CIE IGCSE Mathematics· 7.1· 25 min read

1. Core Tier: 4 Basic Transformations★★☆☆☆⏱ 5 min

There are 4 core transformations you need to master for the Core tier, each mapping an original shape (object) to a new shape (image). All preserve the side lengths and angles of the shape except enlargement, which preserves proportionality and angles.

📘 Definition

Transformation

A mapping of every point on an object shape to a corresponding point on an image shape, following a fixed rule.

Reflection: Flip over a mirror line, all points equidistant from the line on either side
Rotation: Turn around a fixed centre point, by a fixed angle and direction
Translation: Slide the shape by a fixed distance horizontally and vertically, no rotation or flipping
Enlargement: Scale the shape up or down by a fixed factor, from a fixed centre point

📐 Worked Example

Translate the triangle with vertices at (1,1), (1,3), (3,1) by the column vector $(2 - 1)$

1
Add the x-component of the vector to each x-coordinate, and the y-component to each y-coordinate.
2
$(1+2, 1-1) = (3,0); (1+2, 3-1) = (3,2); (3+2,1-1) = (5,0)$
3
Plot the new vertices and connect to form the translated image.

Exam tip:

When describing translations, always use column vectors, not words like 'move right 2' — this avoids ambiguity and guarantees marks.

2. Core Transformations: Reflection & Rotation★★★☆☆⏱ 6 min

Core tier only requires you to reflect shapes in horizontal (y = constant) or vertical (x = constant) lines, and rotate by 90°, 180°, 270° around a specified centre.

📘 Definition

Invariant Point

A point that does not change position after a transformation, e.g. points on a reflection mirror line are invariant.

📐 Worked Example

Reflect the point (2, 5) in the horizontal line y = 3.

1
Calculate the vertical distance of the point from the mirror line: 5 - 3 = 2 units above the line.
2
Move the same distance below the mirror line to get the image point: y-coordinate = 3 - 2 = 1.
3
$Image point is (2, 1)$

📐 Worked Example

Rotate the point (4, 1) 90° clockwise about the origin (0,0).

1
Use the rule for 90° clockwise rotation about origin: swap x and y coordinates, then reverse the sign of the new y coordinate.
2
$(4,1) → (1, -4)$
3
Verify by tracing the point and turning your page 90° clockwise if you are unsure.

Exam tip:

Tracing paper is allowed in all CIE IGCSE maths exams — use it for rotation questions to avoid calculation errors, especially if the centre of rotation is not the origin.

3. Core Transformations: Enlargement★★★☆☆⏱ 5 min

Core tier enlargements use positive or fractional positive scale factors, from a specified centre. The image will be the same shape as the object, but larger or smaller, with all sides scaled by the scale factor.

📘 Definition

Scale Factor (Enlargement)

The ratio of the length of a side of the image to the length of the corresponding side of the original object.

📐 Worked Example

Enlarge the triangle with vertices (1,1), (2,1), (1,3) by scale factor 2, with centre of enlargement at (0,0).

1
Multiply each coordinate of the object vertices by the scale factor 2.
2
$(1×2, 1×2) = (2,2); (2×2, 1×2) = (4,2); (1×2, 3×2) = (2,6)$
3
Check that lines from the centre (0,0) through each object vertex pass through the corresponding image vertex.

Exam tip:

If you are asked for the scale factor of an enlargement, always divide an image side length by the object side length, not the other way around.

4. How to Fully Describe a Transformation (Core)★★★☆☆⏱ 4 min

Most exam questions ask you to describe a transformation fully, rather than just perform it. You must include all required details for each transformation type to get full marks.

Transformation Type	Required Details
Reflection	Mirror line (e.g. x=2, y=-1)
Rotation	Angle, direction (clockwise/anticlockwise), centre of rotation
Enlargement	Scale factor, centre of enlargement
Translation	Column vector

✓ Quick check

A shape is flipped over the line x=4. What is the full description of this transformation?
Reveal answer
Reflection in the line x=4 —
You only need to state the transformation type and mirror line for full marks.
A shape is turned 180° around the point (2,3). What detail is missing from the description?
Reveal answer
No details are missing: 180° rotations do not require a direction, as clockwise and anticlockwise give the same result. —
Direction is only required for 90° and 270° rotations.

5. Extended Tier Additional Content★★★★☆Extended only⏱ 7 min

Extended tier adds three extra skill areas: reflections in any line (including y=x, y=-x, y=a), rotation about any centre, negative scale factor enlargements, and combined transformations.

📐 Worked Example

Reflect the point (3, 1) in the line y = x.

1
The rule for reflection in y = x is to swap the x and y coordinates of the point.
2
$(3,1) → (1, 3)$

📐 Worked Example

Enlarge the point (2, 2) by scale factor -2, centre at (0,0).

1
First multiply coordinates by the signed scale factor. Negative scale factors produce images on the opposite side of the centre of enlargement from the original object.
2
$(2×-2, 2×-2) = (-4, -4)$

📐 Worked Example

A shape is first reflected in y = x, then translated by $(10)$ . What is the image of (2, 3) after both transformations?

1
Perform the first transformation first: reflection in y = x swaps coordinates, so (2,3) → (3,2).
2
Perform the second transformation: add the column vector components to (3,2):
3
$(3+1, 2+0) = (4,2)$
4
The final image point is (4,2).

Exam tip:

When combining transformations, always perform them in the order given in the question — reversing the order will usually give a different result.

6. Common Pitfalls

Wrong move:

Forgetting to include the centre of rotation/enlargement when describing a transformation.

Why:

Examiners require all details to award full marks, missing the centre loses 1-2 marks per question.

Correct move:

Always list all required details per transformation type using the reference table in this guide.

Wrong move:

Using words instead of column vectors to describe translations, e.g. "move 3 right and 2 up".

Why:

Examiners prefer column vectors to avoid ambiguity, some mark schemes only accept column vectors.

Correct move:

Always write translations as column vectors $(a b)$ where a is horizontal displacement, b vertical.

Wrong move:

Calculating scale factor as object length divided by image length instead of the reverse.

Why:

This gives the reciprocal of the correct scale factor, leading to lost marks.

Correct move:

Scale factor = image side length ÷ corresponding object side length.

Wrong move:

Performing combined transformations in the wrong order.

Why:

Transformations are not commutative, so reversing the order gives a different final image.

Correct move:

Always apply transformations in the exact order stated in the question.

Wrong move:

Assuming negative scale factors are used in Core tier questions.

Why:

Negative scale factors are exclusively Extended tier content, so Core students will never be asked about them.

Correct move:

Core students can ignore any question mention of negative scale factors if they appear in practice mixed-tier papers.

7. Quick Reference Cheatsheet

Transformation	Core Rule	Extended Additions
Reflection	Mirror line horizontal/vertical only, state line equation	Reflect in any line (y=x, y=-x, y=a, etc.), state full line equation
Rotation	Multiples of 90°, specified centre, state angle, direction, centre	Rotate around any centre, same required details as Core
Translation	State column vector $(a b)$	No additional rules
Enlargement	Positive/fractional positive scale factor, state scale factor + centre	Negative scale factors allowed, state signed scale factor + centre
Combined Transformations	Not tested in Core	Find single equivalent transformation, or apply multiple transformations in order

8. Frequently Asked

How many details do I need to give when describing a transformation?

For full marks, always include all required details per type:
- Reflection: specify the mirror line (e.g. $x = 3$ , $y = x$ )
- Rotation: specify angle, direction (clockwise/anticlockwise), and centre of rotation
- Enlargement: specify scale factor and centre of enlargement
- Translation: specify the column vector

Do negative scale factor enlargements come up in Core tier?

No, negative scale factors are only tested in the Extended tier (Papers 2 and 4). Core students only need to know positive and fractional positive scale factors.

Going deeper

official_documentCIE IGCSE 0580 2025-2027 SyllabusOfficial syllabus for reference

What's Next

Now that you have mastered transformations for CIE IGCSE 0580, you are ready to move on to related topics in the Transformations and Vectors unit, starting with column vectors and their applications. Next, practice applying your transformation skills to past paper questions, paying special attention to the required details for describing transformations to avoid losing easy marks. For Extended students, make sure you practice combined transformation questions, which are frequently tested as 3-4 mark questions in Paper 2 and Paper 4. You should also consolidate your coordinate geometry skills to quickly calculate mirror lines and centres of rotation when they are not given to you in the question.