Apply combined transformations in a stated order
Apply two transformations in a stated order, record the complete intermediate image and compare the reversed order without assuming either universal commutation or universal failure to commute.
Exam scope and assessment notes
These twelve shared lessons apply to Foundation and inherited Higher for F5.2A–M; no extra Higher row is added. Keep named corners, signed turns, equivalent mirror equations, exact fractions, positive factors and the freely chosen-centre and identity exceptions. General-angle coordinates are final3dp approximations of unrounded geometry. Written explanations need human review; coordinate agreement does not certify proof or physical construction. Linear November2026/June2027 entry and regional-centre rules remain separate from modular awards. Book2 Shape and Space7 tags and Hubs66–71 are navigation only: map223–248 differs from proof222/summary247/next248, with chapter/Hub bodies unavailable.
Before you begin
- Apply each transformation to a complete labelled polygon.
- Retain exact coordinates through successive operations.
- Use inverse vectors, signed angles, reflections and reciprocal positive factors.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
To apply T and then R, which points are used as the object for R?
What you will learn
- Use the first complete image as the object of the second operation.
- Compare reversed-order results while preserving the stated centres, mirrors and vectors.
- Distinguish reversing operation order from constructing the inverse of a composition.
Polygon ABC has A(1,1), B(4,1), C(2,3). In the given order, translate by the column vector with top entry 3 and bottom entry 1, then rotate about (0,0) by 90 degrees, using positive for anticlockwise. Apply the two stated operations in the supplied order, recording the intermediate and final named vertices. Then reverse the order and compare; do not assume the outcomes must differ.
Describe your operation, construct every named image point, and record your actual directed traces. Only the question supplies the givens. The board does not transform a shape or recover a missing parameter for you.
Both Cartesian directions have equal drawing scale. Blue is supplied geometry, amber is my actual work, purple is dirty retained work, and green is a separately gated reference. Screen size is not physical instrument calibration.
Actual boundaries retain their entered order, closure, concavity and wrong or incomplete points. No reflected corner, rotation endpoint, mirror foot or target polygon is filled automatically. Construction rays continue beyond their anchors; mirror lines continue both ways; joining segments keep their original endpoints.
Supplied translation vector (3, 1). This description does not generate a target boundary.
Supplied rotation 90° about (0, 0). This description does not generate a target boundary.
This finite fixed-case comparison is not proof marking, marks, mastery, physical construction calibration or specialist/formal assessment approval. General-angle points stay unrounded; a separately requested three-decimal written table is an approximation.
Actual operation 1
No actual construction is recorded for this action.
Choose a point slot before adding a keyboard coordinate or picking on the board. Named picks retain exact given or current clean recorded coordinates. Free picks retain their unrounded actual planar coordinates; they do not snap to an expected result.
My written coordinates, quantities and reasoning
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Write both coordinates as x,y; exact fractions and finite decimals are supported.
Choose Yes or No after checking your current construction.
Explain your actual correspondence, construction and conditions. A written attempt is not an automatically verified proof.
Explain your actual correspondence, construction and conditions. A written attempt is not an automatically verified proof.
Explain your actual correspondence, construction and conditions. A written attempt is not an automatically verified proof.
This sequence is optional. If you add operations, complete every chosen parameter or remove the sequence. The tool generates no inverse for you.
These original cases support mathematical self-checking. They do not award marks, mastery, proof approval, physical construction competence, specialist signoff or formal assessment readiness. Positive scale factors only; unchanged images do not uniquely recover a centre. Keep general-angle construction coordinates unrounded and separately requested written coordinates at three decimal places.
Track two complete movements in order
For“first T, then R”, apply T to every object vertex and keep that full intermediate image. Apply R to those intermediate points, using R’s stated centre, mirror or vector in the original coordinate plane. Do not secretly move its centre along with the first figure unless the question explicitly tells you to do so.
Use a second set of labels or a clear table for the intermediate and final coordinates. A concave polygon needs all of its vertices at both stages. Combining two rules mentally can hide a missing translation, a changed pivot or a reflection of the original object instead of the required intermediate one.
Compare the reversed order honestly
To reverse the order, begin again with the original object, apply R first and then T. Compare every final named vertex with the original-order result. Many pairs give different results, but it is false that transformations always fail to commute: the actual operations and their geometric parameters matter.
For example, reflections in perpendicular intersecting mirrors compose to a half turn about their intersection. Reversing those two reflections gives the same half turn, because +180° and−180° have the same final effect. By contrast, a translation and a rotation about a fixed centre generally produce different images when their order is exchanged.
Do not confuse reversed order with the inverse
The inverse of“first T, then R” is“first R inverse, then T inverse”. Both the order and each individual movement must be reversed. Merely applying R then T repeats the forward operations in a different order; it generally does not return the object.
These ordered examples are chosen practice alongside the public book’s combined-transformations heading, rather than an extra lettered syllabus row. Explain the full labelled construction and compare the actual results. Written explanations still need human review. Coordinate agreement does not replace checking the reasoning, physical construction accuracy or any separately required formal assessment.
Sources for this lesson
- Pearson Mathematics A linear specification · Issue2 · Transformation geometry Foundation printed23/physical29 and Higher inheritance printed38/physical44
- Pearson 2026/2027 International GCSE entry manual · centre regions physical3 and Mathematics A physical25
- Pearson literal second-edition book/Hub map · Book2 Shape and Space7 physical12 · navigation only
Pause and explain
What undoes“translate by v, then rotate by θ about C”?
Worked example
Polygon ABC has A(1,1), B(4,1), C(2,3). In the given order, translate by the column vector with top entry 3 and bottom entry 1, then rotate about (0,0) by 90 degrees, using positive for anticlockwise. Apply the two stated operations in the supplied order, recording the intermediate and final named vertices. Then reverse the order and compare; do not assume the outcomes must differ.
Show the worked solution
- Start with the original figure and apply translation by column[3;1]. The complete intermediate image is A′=(4,2), B′=(7,2), C′=(5,4). Keep every vertex as the input to the second operation.
- Now apply rotation about (0,0) through 90° (anticlockwise for the stated sign) to that intermediate image, retaining the stated original-plane parameters. The final image is A″=(-2,4), B″=(-2,7), C″=(-4,5).
- Starting again from the original object and reversing only the order gives A_rev=(2,2), B_rev=(2,5), C_rev=(0,3). These final named points differ, so these particular operations do not commute.
- Reversed forward order is distinct from the inverse. To undo the required original composition, use rotation about (0,0) through -90° (clockwise for the stated sign); then translation by column[-3;-1]. This reverses both the order and each individual operation, and returns every final point to the original object.
Answer Intermediate: A′=(4,2), B′=(7,2), C′=(5,4). Final: A″=(-2,4), B″=(-2,7), C″=(-4,5). Reversed order: A_rev=(2,2), B_rev=(2,5), C_rev=(0,3). Different final images; this pair does not commute.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Polygon ABCD has A(0,0), B(3,0), C(4,2), D(1,3). In the given order, reflect in the line x=1, then reflect in the line y=2. Apply the two stated operations in the supplied order, recording the intermediate and final named vertices. Then reverse the order and compare; do not assume the outcomes must differ.
Give me a hint
Keep the full first image, apply the second operation to it and compare reversed order from the original.
Compare my reasoning
- Start with the original figure and apply reflection in x=1. The complete intermediate image is A′=(2,0), B′=(-1,0), C′=(-2,2), D′=(1,3). Keep every vertex as the input to the second operation.
- Now apply reflection in y=2 to that intermediate image, retaining the stated original-plane parameters. The final image is A″=(2,4), B″=(-1,4), C″=(-2,2), D″=(1,1).
- Starting again from the original object and reversing only the order gives A_rev=(2,4), B_rev=(-1,4), C_rev=(-2,2), D_rev=(1,1). These final named points agree: the perpendicular reflections compose to the same half turn about(1,2) in either order.
- Reversed forward order is distinct from the inverse. To undo the required original composition, use reflection in y=2; then reflection in x=1. This reverses both the order and each individual operation, and returns every final point to the original object.
Intermediate: A′=(2,0), B′=(-1,0), C′=(-2,2), D′=(1,3). Final: A″=(2,4), B″=(-1,4), C″=(-2,2), D″=(1,1). Reversed order: A_rev=(2,4), B_rev=(-1,4), C_rev=(-2,2), D_rev=(1,1). Same final image; these perpendicular reflections commute.
Look for these in your work
- Use the first complete image as the object of the second operation.
- Compare reversed-order results while preserving the stated centres, mirrors and vectors.
- Distinguish reversing operation order from constructing the inverse of a composition.
Polygon ABCDEF has A(0,0), B(4,0), C(4,1), D(1,1), E(1,3), F(0,3). In the given order, enlarge about (1,0) with positive factor 2, then rotate about (0,0) by 90 degrees, using positive for anticlockwise. Apply the two stated operations in the supplied order, recording the intermediate and final named vertices. Then reverse the order and compare; do not assume the outcomes must differ.
Give me a hint
Keep the full first image, apply the second operation to it and compare reversed order from the original.
Compare my reasoning
- Start with the original figure and apply enlargement about (1,0) with positive factor 2. The complete intermediate image is A′=(-1,0), B′=(7,0), C′=(7,2), D′=(1,2), E′=(1,6), F′=(-1,6). Keep every vertex as the input to the second operation.
- Now apply rotation about (0,0) through 90° (anticlockwise for the stated sign) to that intermediate image, retaining the stated original-plane parameters. The final image is A″=(0,-1), B″=(0,7), C″=(-2,7), D″=(-2,1), E″=(-6,1), F″=(-6,-1).
- Starting again from the original object and reversing only the order gives A_rev=(-1,0), B_rev=(-1,8), C_rev=(-3,8), D_rev=(-3,2), E_rev=(-7,2), F_rev=(-7,0). These final named points differ, so these particular operations do not commute.
- Reversed forward order is distinct from the inverse. To undo the required original composition, use rotation about (0,0) through -90° (clockwise for the stated sign); then enlargement about (1,0) with positive factor 1/2. This reverses both the order and each individual operation, and returns every final point to the original object.
Intermediate: A′=(-1,0), B′=(7,0), C′=(7,2), D′=(1,2), E′=(1,6), F′=(-1,6). Final: A″=(0,-1), B″=(0,7), C″=(-2,7), D″=(-2,1), E″=(-6,1), F″=(-6,-1). Reversed order: A_rev=(-1,0), B_rev=(-1,8), C_rev=(-3,8), D_rev=(-3,2), E_rev=(-7,2), F_rev=(-7,0). Different final images; this pair does not commute.
Look for these in your work
- Use the first complete image as the object of the second operation.
- Compare reversed-order results while preserving the stated centres, mirrors and vectors.
- Distinguish reversing operation order from constructing the inverse of a composition.
Polygon ABCD has A(-2,1), B(1,1), C(2,4), D(-1,3). In the given order, reflect in the line y=x (equivalently y-x=0), then translate by the column vector with top entry 2 and bottom entry -1. Apply the two stated operations in the supplied order, recording the intermediate and final named vertices. Then reverse the order and compare; do not assume the outcomes must differ.
Give me a hint
Keep the full first image, apply the second operation to it and compare reversed order from the original.
Compare my reasoning
- Start with the original figure and apply reflection in y=x (equivalently y−x=0). The complete intermediate image is A′=(1,-2), B′=(1,1), C′=(4,2), D′=(3,-1). Keep every vertex as the input to the second operation.
- Now apply translation by column[2;-1] to that intermediate image, retaining the stated original-plane parameters. The final image is A″=(3,-3), B″=(3,0), C″=(6,1), D″=(5,-2).
- Starting again from the original object and reversing only the order gives A_rev=(0,0), B_rev=(0,3), C_rev=(3,4), D_rev=(2,1). These final named points differ, so these particular operations do not commute.
- Reversed forward order is distinct from the inverse. To undo the required original composition, use translation by column[-2;1]; then reflection in y=x (equivalently y−x=0). This reverses both the order and each individual operation, and returns every final point to the original object.
Intermediate: A′=(1,-2), B′=(1,1), C′=(4,2), D′=(3,-1). Final: A″=(3,-3), B″=(3,0), C″=(6,1), D″=(5,-2). Reversed order: A_rev=(0,0), B_rev=(0,3), C_rev=(3,4), D_rev=(2,1). Different final images; this pair does not commute.
Look for these in your work
- Use the first complete image as the object of the second operation.
- Compare reversed-order results while preserving the stated centres, mirrors and vectors.
- Distinguish reversing operation order from constructing the inverse of a composition.
Common mistakes
- Applying the second transformation to the original rather than the intermediate image.
- Moving a stated centre or mirror without permission.
- Assuming all operations commute, or confusing reversed order with the inverse.
What can you explain now?
Does reversing the order of two transformations always produce a different final image?
Compare with the explanation
No. Some pairs commute, including reflections in perpendicular intersecting lines.
The actual combined map must be calculated or justified; those two reflections give the same half turn about their intersection in either order.
After trying it yourself, choose your next review. This is your self-assessment.
Your review choice appears on Today. Sign in to sync it across devices.
Make it stick
Explain how to record a two-step transformation, compare reversed order and write the true inverse, including a commuting example.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.