Rotate through general degree angles
Construct general signed-angle rotations using a true pivot and unchanged radii, while separating approximate written coordinates from unrounded geometric positions.
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
- Use the geometric definition of rotation and signed angles.
- Read a protractor or turn a traced figure about a marked centre.
- Round final decimal values; calculator trigonometry can provide an optional coordinate check.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What must be copied when a ray from the centre is turned through a general angle?
What you will learn
- Turn complete figures through supplied non-quarter degree angles.
- Use tracing or measured rays and radii without substituting a reflection or a quarter-turn shortcut.
- Write requested numerical coordinates to 3 decimal places while retaining unrounded construction geometry.
Polygon ABC has A(1,1), B(4,1), C(2,3). In the given order, rotate about (0,0) by 60 degrees, using positive for anticlockwise. Construct and label its image under the stated transformation; record the corresponding vertices and explain the method. If using numerical coordinates, round only final values to 3 decimal places; retain unrounded geometry during construction.
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 rotation 60° 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 x,y with three decimal places for each coordinate. Keep the actual construction unrounded.
Write x,y with three decimal places for each coordinate. Keep the actual construction unrounded.
Write x,y with three decimal places for each coordinate. Keep the actual construction unrounded.
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.
A general angle uses the same rotation definition
A rotation need not be a quarter or half turn. Place the pivot at the given centre, copy each centre-to-vertex radius and turn it through the stated signed angle. Tracing paper can turn the complete figure together; alternatively, measure each new ray and transfer its original radius before joining the labelled image boundary.
Keep the angle measured from the object ray towards its image ray. The same signed angle applies to every vertex, including those on different sides of the centre. A protractor construction is approximate in practice, so record the intended exact centre and angle separately from any reading made from a drawn diagram.
Check coordinates without changing the construction
A numerical check may use u=x−h and v=y−k about centre(h,k). Turning these local components through θ gives u′=u cosθ−v sinθ and v′=u sinθ+v cosθ; adding(h,k) returns the image position. Use degree mode. This is a computational check of the same rotation, not a replacement for explaining the geometric pivot, angle and radius.
These calculations often produce irrational coordinates even when the object uses integers. Keep the unrounded values while checking distances, angles and the inverse movement. If the task requests coordinates to 3 decimal places, round only the final written coordinate values; do not repeatedly turn an already rounded image or reshape the figure to fit a decimal grid.
Distinguish model values and drawn readings
The stated rotation is exact as a mathematical transformation, whereas a measured point on paper or a screen gives an approximate reading at the drawing’s scale. A decimal coordinate table is also an approximation unless the value terminates exactly. Label approximations clearly and keep the names in the original boundary order, including a concave corner.
The inverse uses the same centre and the negative angle. Applying it to the unrounded image should return the object, and every centre-to-vertex radius should agree. Equivalent angles differing by 360° are legitimate descriptions. Physical protractor accuracy and complete instrument work still need separate practical observation; a coordinate comparison does not certify them.
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
A non-quarter rotation gives x′≈2.7182818. The task asks for 3 decimal places. Which record is appropriate?
Worked example
Polygon ABC has A(1,1), B(4,1), C(2,3). In the given order, rotate about (0,0) by 60 degrees, using positive for anticlockwise. Construct and label its image under the stated transformation; record the corresponding vertices and explain the method. If using numerical coordinates, round only final values to 3 decimal places; retain unrounded geometry during construction.
Show the worked solution
- For A, subtract the pivot (0,0) to obtain the local displacement (1,1). Turn that radius through 60° with positive meaning anticlockwise; preserve its distance from the pivot. An optional numerical check substitutes u=1, v=1 and θ=60° into(u cosθ−v sinθ,u sinθ+v cosθ), in degree mode; retain those unrounded values before adding the centre.
- Use the same signed turn for every vertex, then restore the centre position. The full labelled image is A′≈(-0.366,1.366), B′≈(1.134,3.964), C′≈(-1.598,3.232). These numerical coordinates are final 3 decimal place approximations; the construction uses unrounded radii and positions.
- Reconnect the image in boundary order A′→B′→C′→A′, retaining all corners. The inverse is rotation about (0,0) through -60° (clockwise for the stated sign); applied to the unrounded image it returns the object and verifies both pivot and direction.
Answer A′≈(-0.366,1.366), B′≈(1.134,3.964), C′≈(-1.598,3.232) (each coordinate 3 decimal places). Centre (0,0) and signed angle 60° specify the exact rotation; use unrounded geometry.
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, rotate about (1,1) by -45 degrees, using positive for anticlockwise. Construct and label its image under the stated transformation; record the corresponding vertices and explain the method. If using numerical coordinates, round only final values to 3 decimal places; retain unrounded geometry during construction.
Give me a hint
Copy each radius and signed turn; keep unrounded geometry and round only the final coordinate record.
Compare my reasoning
- For A, subtract the pivot (1,1) to obtain the local displacement (-1,-1). Turn that radius through -45° with positive meaning anticlockwise; preserve its distance from the pivot. An optional numerical check substitutes u=-1, v=-1 and θ=-45° into(u cosθ−v sinθ,u sinθ+v cosθ), in degree mode; retain those unrounded values before adding the centre.
- Use the same signed turn for every vertex, then restore the centre position. The full labelled image is A′≈(-0.414,1.000), B′≈(1.707,-1.121), C′≈(3.828,-0.414), D′≈(2.414,2.414). These numerical coordinates are final 3 decimal place approximations; the construction uses unrounded radii and positions.
- Reconnect the image in boundary order A′→B′→C′→D′→A′, retaining all corners. The inverse is rotation about (1,1) through 45° (anticlockwise for the stated sign); applied to the unrounded image it returns the object and verifies both pivot and direction.
A′≈(-0.414,1.000), B′≈(1.707,-1.121), C′≈(3.828,-0.414), D′≈(2.414,2.414) (each coordinate 3 decimal places). Centre (1,1) and signed angle -45° specify the exact rotation; use unrounded geometry.
Look for these in your work
- Turn complete figures through supplied non-quarter degree angles.
- Use tracing or measured rays and radii without substituting a reflection or a quarter-turn shortcut.
- Write requested numerical coordinates to 3 decimal places while retaining unrounded construction geometry.
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, rotate about (-1,2) by 120 degrees, using positive for anticlockwise. Construct and label its image under the stated transformation; record the corresponding vertices and explain the method. If using numerical coordinates, round only final values to 3 decimal places; retain unrounded geometry during construction.
Give me a hint
Copy each radius and signed turn; keep unrounded geometry and round only the final coordinate record.
Compare my reasoning
- For A, subtract the pivot (-1,2) to obtain the local displacement (1,-2). Turn that radius through 120° with positive meaning anticlockwise; preserve its distance from the pivot. An optional numerical check substitutes u=1, v=-2 and θ=120° into(u cosθ−v sinθ,u sinθ+v cosθ), in degree mode; retain those unrounded values before adding the centre.
- Use the same signed turn for every vertex, then restore the centre position. The full labelled image is A′≈(0.232,3.866), B′≈(-1.768,7.330), C′≈(-2.634,6.830), D′≈(-1.134,4.232), E′≈(-2.866,3.232), F′≈(-2.366,2.366). These numerical coordinates are final 3 decimal place approximations; the construction uses unrounded radii and positions.
- Reconnect the image in boundary order A′→B′→C′→D′→E′→F′→A′, retaining all corners. The inverse is rotation about (-1,2) through -120° (clockwise for the stated sign); applied to the unrounded image it returns the object and verifies both pivot and direction.
A′≈(0.232,3.866), B′≈(-1.768,7.330), C′≈(-2.634,6.830), D′≈(-1.134,4.232), E′≈(-2.866,3.232), F′≈(-2.366,2.366) (each coordinate 3 decimal places). Centre (-1,2) and signed angle 120° specify the exact rotation; use unrounded geometry.
Look for these in your work
- Turn complete figures through supplied non-quarter degree angles.
- Use tracing or measured rays and radii without substituting a reflection or a quarter-turn shortcut.
- Write requested numerical coordinates to 3 decimal places while retaining unrounded construction geometry.
Polygon ABCD has A(-2,1), B(1,1), C(2,4), D(-1,3). In the given order, rotate about (2,-2) by -30 degrees, using positive for anticlockwise. Construct and label its image under the stated transformation; record the corresponding vertices and explain the method. If using numerical coordinates, round only final values to 3 decimal places; retain unrounded geometry during construction.
Give me a hint
Copy each radius and signed turn; keep unrounded geometry and round only the final coordinate record.
Compare my reasoning
- For A, subtract the pivot (2,-2) to obtain the local displacement (-4,3). Turn that radius through -30° with positive meaning anticlockwise; preserve its distance from the pivot. An optional numerical check substitutes u=-4, v=3 and θ=-30° into(u cosθ−v sinθ,u sinθ+v cosθ), in degree mode; retain those unrounded values before adding the centre.
- Use the same signed turn for every vertex, then restore the centre position. The full labelled image is A′≈(0.036,2.598), B′≈(2.634,1.098), C′≈(5.000,3.196), D′≈(1.902,3.830). These numerical coordinates are final 3 decimal place approximations; the construction uses unrounded radii and positions.
- Reconnect the image in boundary order A′→B′→C′→D′→A′, retaining all corners. The inverse is rotation about (2,-2) through 30° (anticlockwise for the stated sign); applied to the unrounded image it returns the object and verifies both pivot and direction.
A′≈(0.036,2.598), B′≈(2.634,1.098), C′≈(5.000,3.196), D′≈(1.902,3.830) (each coordinate 3 decimal places). Centre (2,-2) and signed angle -30° specify the exact rotation; use unrounded geometry.
Look for these in your work
- Turn complete figures through supplied non-quarter degree angles.
- Use tracing or measured rays and radii without substituting a reflection or a quarter-turn shortcut.
- Write requested numerical coordinates to 3 decimal places while retaining unrounded construction geometry.
Common mistakes
- Using quarter-turn swaps for a general angle.
- Using radians or reversing the measured turn.
- Rounding coordinates before the geometry or inverse check is complete.
What can you explain now?
Does writing an image coordinate to 3 decimal places make its rounded point the exact rotation target?
Compare with the explanation
No. The written coordinate is an approximation to the unrounded rotated point.
The exact centre and angle define the transformation. Rounding is reserved for the requested final numerical record.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Describe a general-angle construction and explain which values remain exact, which readings are approximate and when final coordinates are rounded.
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.