Enlarge shapes with signed and fractional scales
Use kI₂ to scale every point about the origin,distinguishing signed scale from distance multiplier across all four practice modes.
Section 5 · Matrices (5A–G teaching map;self-check practice)
Exam scope and assessment notes
Original Mathematics B Matrices5A–G candidate: twelve teaching lessons,twelve worked examples,36 explained guided/independent/application practice tasks,and48 bound four-stage cases;all four specified reflection lines,rotations and enlargements have dedicated complete four-stage bundles. Matrix data,addition,multiplication,scalars,identity/zero,nonsingular2×2inverse,and plane transformations retain their own original givens. The learner enters blank working operands,intermediate results,constructions and separate final answers;edits,withdrawal,clearing,stage/reset and source/session/revision changes withhold old comparisons and explained references. Exact supported real square-root entries cover30°,45° and60° rotations in addition to quarter turns;the general cosine/sine formula is taught,while more general numerical trigonometry and equivalent forms outside the finite algebra engine require review. Written meanings,dimensions,units,geometric descriptions,drawn shapes and empirical validity need human review. All7Matrices source rows have reviewed structural teaching/practice bundles only while every original complete record remains intact. Row5Fjointly requires all six named transformation-family records,each with all four stages. Other Mathematics B source rows remain unlinked; see the current course map;the wider Pearson curriculum remains incomplete. ISBN9780435044107 is metadata only;no full book body,chapter sequence or Hub mapping is verified. Single Higher-tier linear4MB1;entry context November2026/June2027only. No MathematicsA,Foundation,modular or later-series inheritance. No fresh mounted-browser,hosted four-stage interaction,saved progress,official marks,mastery,specialist approval or formal assessment readiness is established.
Before you begin
- Signed exact rational arithmetic and fractions
- Rows,columns and labelled coordinate pairs
- Original matrix orders and row–column multiplication
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Under scale−3/2 about the origin,what happens to distance and ray direction?
What you will learn
- Map column vectors: explain and apply the stated matrix method.
- Construct an enlargement from its scale: explain and apply the stated matrix method.
- Retain the sign and the original centre: explain and apply the stated matrix method.
- Review a whole shape and its interpretation: explain and apply the stated matrix method.
Matrices: build,check and explain
Worked practice
Construct each stated enlargement matrix with centre at the origin. Transform all three supplied vertices and draw the image on the original axes. Explain the scale factor,centre and any change in direction. Distinguish the signed scale from its positive distance multiplier.
| 2 | 1 |
| -1 | 3 |
| 0 | -2 |
- enlargement of scale 2 about the origin
Construct these matrices yourself; use sqrt(2)/2 or sqrt(3)/2 for exact square-root entries.
Record your actual working
Enter original operands and each intermediate result. Final answers will be recorded separately. 0 of 35 fields entered.
Current entries need recording.
Enter separate final answers
Enter your own answers without copying them into the working form. 0 of 11 fields entered.
Current entries need recording.
Record your complete current operands,intermediate results,matrix constructions and method.
Review the original row/column meanings, units, written dimension/method argument, and any drawn shape or geometric description. A comparison of numbers does not approve these.
What these checks can establish
- Bounded exact rational and supported simple real square-root expressions; no arbitrary code evaluation or unknown-variable repair.
- At most three rows and columns; determinant and inverse tasks use nonsingular two by two matrices. Refusing a singular inverse adds no singular-matrix syllabus requirement.
- General rotations are taught by the cosine/sine matrix. Exact 30°,45° and60° rotations supplement quarter turns; more general numerical angle proposals need explicitly reviewed trigonometric precision.
- Equivalent expressions outside the inherited finite symbolic forms need human review rather than automatic failure-as-mathematical-proof. No geometric explanation,drawn shape,official marks,mastery,specialist approval or formal assessment readiness is established by numerical agreement.
- All work operands, intermediate results and separate final answers begin blank. A correct separate answer never repairs wrong original working.
- Working records retain original row/column term operands and results; matrix construction and both inverse checks are required where requested. These fixed comparisons do not prove a written argument or a drawn transformation.
- Edits,cleared groups,withdrawal,reset,stage switches and source/session/generation/revision changes invalidate earlier results and withhold the explained reference. Direct changes to recorded fields also withdraw readiness.
- A complete incorrect attempt may study an explanation without being marked correct. Reference study is not evidence of mastery or assessment readiness.
This practice stays in the current open activity. No saved account progress, official mark or mastery result is awarded here.
Map column vectors
Represent a point (x,y) by [x;y]. For M=[a,b;c,d], its image is [ax+by;cx+dy]. The first column of M is the image of (1,0),and the second column is the image of (0,1). This gives a way to construct the matrix from its geometric description.
Map every labelled vertex of a polygon,plot the original and image points on common labelled axes,and join corresponding vertices in their original order. Correct coordinates alone do not check the axes,scale or joined shape in a drawing.
Construct an enlargement from its scale
An enlargement with centre at the origin sends(x,y) to(kx,ky). Its matrix is[k,0;0,k],because the coordinate basis vectors map to(k,0) and(0,k). Both coordinates receive the same scalar.
For k=2,the point(3,−2) maps to(6,−4). For k=1/2,it maps to(3/2,−1). A positive fractional scale less than one reduces distances from the origin while retaining each ray’s direction.
Retain the sign and the original centre
For k=−2,the point(3,−2) maps to(−6,4). The image is on the opposite ray from the origin and its distance from the origin is multiplied by2. The signed scale is−2;the distance multiplier is|−2|=2.
Scale1 leaves all points fixed. Scale0 collapses all points to the origin and has no inverse;this boundary observation does not turn the inverse lesson into a singular-matrix assessment requirement. A different centre would need a different description and is not silently represented by kI₂.
Review a whole shape and its interpretation
This lesson gives positive,positive-fractional,negative and negative-fractional scales across dedicated Worked,Guided,Independent and Application tasks. Construct the matrix before mapping every labelled vertex.
Draw the original and image shapes on the same axes,retaining corresponding vertices. State the centre and signed scale explicitly. A numerical coordinate match does not check your axes,drawing or written geometric interpretation.
Sources for this lesson
Pause and explain
Under scale−3/2 about the origin,what happens to distance and ray direction?
Worked example
Construct each stated enlargement matrix with centre at the origin. Transform all three supplied vertices and draw the image on the original axes. Explain the scale factor,centre and any change in direction. Distinguish the signed scale from its positive distance multiplier. Vertices=[2, 1; -1, 3; 0, -2] (columns x,y); transformations=enlargement of scale 2 about the origin.
Show the worked solution
- Represent each original vertex as a column vector. Keep its x-coordinate first and its y-coordinate second.
- enlargement of scale 2 about the origin: the image of (1,0) is (2,0) and the image of (0,1) is (0,2). These are the first and second matrix columns respectively.
- Use the stated scale on both diagonal entries and zero off the diagonal. The signed scale determines the ray direction;its absolute value determines the distance multiplier. Keep the centre at the origin.
- For every vertex,calculate both matrix-row dot products with its original coordinate column. Keep all signed terms.
- Plot and label the original and image vertices on common axes and join corresponding edges in the original order. Review the geometric description and any fixed-line or distance claim separately from the numerical comparison.
- Construct the matrix: enlargement of scale 2 about the origin: [2, 0; 0, 2].
- enlargement of scale 2 about the origin: vertex 1: row 1 · column 1: (2)*(2) + (0)*(1) = 4.
- enlargement of scale 2 about the origin: vertex 1: row 2 · column 1: (0)*(2) + (2)*(1) = 2.
- enlargement of scale 2 about the origin: vertex 2: row 1 · column 1: (2)*(-1) + (0)*(3) = -2.
- enlargement of scale 2 about the origin: vertex 2: row 2 · column 1: (0)*(-1) + (2)*(3) = 6.
- enlargement of scale 2 about the origin: vertex 3: row 1 · column 1: (2)*(0) + (0)*(-2) = 0.
- enlargement of scale 2 about the origin: vertex 3: row 2 · column 1: (0)*(0) + (2)*(-2) = -4.
Answer enlargement of scale 2 about the origin — matrix=[2, 0; 0, 2]. enlargement of scale 2 about the origin — images of vertices 1,2,3=[4, 2; -2, 6; 0, -4]. Review graph placement, axes, angle/direction, centre, reflection line and scale factor. General-angle irrational entries are taught but need a separate exact-surds or reviewed numerical interface.
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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.
Construct each stated enlargement matrix with centre at the origin. Transform all three supplied vertices and draw the image on the original axes. Explain the scale factor,centre and any change in direction. Distinguish the signed scale from its positive distance multiplier. Vertices=[3, 1; -1, 4; 0, -2] (columns x,y); transformations=enlargement of scale 1/2 about the origin.
Give me a hint
Keep the original order and labels. Construct each required matrix and retain every original row–column operand or scalar operation; enter the separate final answers yourself.
Compare my reasoning
- Represent each original vertex as a column vector. Keep its x-coordinate first and its y-coordinate second.
- enlargement of scale 1/2 about the origin: the image of (1,0) is (1/2,0) and the image of (0,1) is (0,1/2). These are the first and second matrix columns respectively.
- Use the stated scale on both diagonal entries and zero off the diagonal. The signed scale determines the ray direction;its absolute value determines the distance multiplier. Keep the centre at the origin.
- For every vertex,calculate both matrix-row dot products with its original coordinate column. Keep all signed terms.
- Plot and label the original and image vertices on common axes and join corresponding edges in the original order. Review the geometric description and any fixed-line or distance claim separately from the numerical comparison.
- Construct the matrix: enlargement of scale 1/2 about the origin: [1/2, 0; 0, 1/2].
- enlargement of scale 1/2 about the origin: vertex 1: row 1 · column 1: (1/2)*(3) + (0)*(1) = 3/2.
- enlargement of scale 1/2 about the origin: vertex 1: row 2 · column 1: (0)*(3) + (1/2)*(1) = 1/2.
- enlargement of scale 1/2 about the origin: vertex 2: row 1 · column 1: (1/2)*(-1) + (0)*(4) = -1/2.
- enlargement of scale 1/2 about the origin: vertex 2: row 2 · column 1: (0)*(-1) + (1/2)*(4) = 2.
- enlargement of scale 1/2 about the origin: vertex 3: row 1 · column 1: (1/2)*(0) + (0)*(-2) = 0.
- enlargement of scale 1/2 about the origin: vertex 3: row 2 · column 1: (0)*(0) + (1/2)*(-2) = -1.
enlargement of scale 1/2 about the origin — matrix=[1/2, 0; 0, 1/2]. enlargement of scale 1/2 about the origin — images of vertices 1,2,3=[3/2, 1/2; -1/2, 2; 0, -1]. Review graph placement, axes, angle/direction, centre, reflection line and scale factor. General-angle irrational entries are taught but need a separate exact-surds or reviewed numerical interface.
Look for these in your work
- I retain the original matrices,labels and requested order.
- My working operands,intermediate values and matrix constructions are explicit.
- My separate final answers do not replace my working.
- I review the dimensions,units and any written or geometric argument with the stated limitations.
Construct each stated enlargement matrix with centre at the origin. Transform all three supplied vertices and draw the image on the original axes. Explain the scale factor,centre and any change in direction. Distinguish the signed scale from its positive distance multiplier. Vertices=[4, 1; -1, 5; 0, -2] (columns x,y); transformations=enlargement of scale -2 about the origin.
Give me a hint
Keep the original order and labels. Construct each required matrix and retain every original row–column operand or scalar operation; enter the separate final answers yourself.
Compare my reasoning
- Represent each original vertex as a column vector. Keep its x-coordinate first and its y-coordinate second.
- enlargement of scale -2 about the origin: the image of (1,0) is (-2,0) and the image of (0,1) is (0,-2). These are the first and second matrix columns respectively.
- Use the stated scale on both diagonal entries and zero off the diagonal. The signed scale determines the ray direction;its absolute value determines the distance multiplier. Keep the centre at the origin.
- For every vertex,calculate both matrix-row dot products with its original coordinate column. Keep all signed terms.
- Plot and label the original and image vertices on common axes and join corresponding edges in the original order. Review the geometric description and any fixed-line or distance claim separately from the numerical comparison.
- Construct the matrix: enlargement of scale -2 about the origin: [-2, 0; 0, -2].
- enlargement of scale -2 about the origin: vertex 1: row 1 · column 1: (-2)*(4) + (0)*(1) = -8.
- enlargement of scale -2 about the origin: vertex 1: row 2 · column 1: (0)*(4) + (-2)*(1) = -2.
- enlargement of scale -2 about the origin: vertex 2: row 1 · column 1: (-2)*(-1) + (0)*(5) = 2.
- enlargement of scale -2 about the origin: vertex 2: row 2 · column 1: (0)*(-1) + (-2)*(5) = -10.
- enlargement of scale -2 about the origin: vertex 3: row 1 · column 1: (-2)*(0) + (0)*(-2) = 0.
- enlargement of scale -2 about the origin: vertex 3: row 2 · column 1: (0)*(0) + (-2)*(-2) = 4.
enlargement of scale -2 about the origin — matrix=[-2, 0; 0, -2]. enlargement of scale -2 about the origin — images of vertices 1,2,3=[-8, -2; 2, -10; 0, 4]. Review graph placement, axes, angle/direction, centre, reflection line and scale factor. General-angle irrational entries are taught but need a separate exact-surds or reviewed numerical interface.
Look for these in your work
- I retain the original matrices,labels and requested order.
- My working operands,intermediate values and matrix constructions are explicit.
- My separate final answers do not replace my working.
- I review the dimensions,units and any written or geometric argument with the stated limitations.
A designer is placing a triangular motif on an origin-centred coordinate grid. Construct each stated enlargement matrix with centre at the origin. Transform all three supplied vertices and draw the image on the original axes. Explain the scale factor,centre and any change in direction. Distinguish the signed scale from its positive distance multiplier. Vertices=[5, 1; -1, 6; 0, -2] (columns x,y); transformations=enlargement of scale -3/2 about the origin, enlargement of scale 3/4 about the origin.
Give me a hint
Keep the original order and labels. Construct each required matrix and retain every original row–column operand or scalar operation; enter the separate final answers yourself.
Compare my reasoning
- Represent each original vertex as a column vector. Keep its x-coordinate first and its y-coordinate second.
- enlargement of scale -3/2 about the origin: the image of (1,0) is (-3/2,0) and the image of (0,1) is (0,-3/2). These are the first and second matrix columns respectively.
- enlargement of scale 3/4 about the origin: the image of (1,0) is (3/4,0) and the image of (0,1) is (0,3/4). These are the first and second matrix columns respectively.
- Use the stated scale on both diagonal entries and zero off the diagonal. The signed scale determines the ray direction;its absolute value determines the distance multiplier. Keep the centre at the origin.
- For every vertex,calculate both matrix-row dot products with its original coordinate column. Keep all signed terms.
- Plot and label the original and image vertices on common axes and join corresponding edges in the original order. Review the geometric description and any fixed-line or distance claim separately from the numerical comparison.
- Construct the matrix: enlargement of scale -3/2 about the origin: [-3/2, 0; 0, -3/2].
- enlargement of scale -3/2 about the origin: vertex 1: row 1 · column 1: (-3/2)*(5) + (0)*(1) = -15/2.
- enlargement of scale -3/2 about the origin: vertex 1: row 2 · column 1: (0)*(5) + (-3/2)*(1) = -3/2.
- enlargement of scale -3/2 about the origin: vertex 2: row 1 · column 1: (-3/2)*(-1) + (0)*(6) = 3/2.
- enlargement of scale -3/2 about the origin: vertex 2: row 2 · column 1: (0)*(-1) + (-3/2)*(6) = -9.
- enlargement of scale -3/2 about the origin: vertex 3: row 1 · column 1: (-3/2)*(0) + (0)*(-2) = 0.
- enlargement of scale -3/2 about the origin: vertex 3: row 2 · column 1: (0)*(0) + (-3/2)*(-2) = 3.
- Construct the matrix: enlargement of scale 3/4 about the origin: [3/4, 0; 0, 3/4].
- enlargement of scale 3/4 about the origin: vertex 1: row 1 · column 1: (3/4)*(5) + (0)*(1) = 15/4.
- enlargement of scale 3/4 about the origin: vertex 1: row 2 · column 1: (0)*(5) + (3/4)*(1) = 3/4.
- enlargement of scale 3/4 about the origin: vertex 2: row 1 · column 1: (3/4)*(-1) + (0)*(6) = -3/4.
- enlargement of scale 3/4 about the origin: vertex 2: row 2 · column 1: (0)*(-1) + (3/4)*(6) = 9/2.
- enlargement of scale 3/4 about the origin: vertex 3: row 1 · column 1: (3/4)*(0) + (0)*(-2) = 0.
- enlargement of scale 3/4 about the origin: vertex 3: row 2 · column 1: (0)*(0) + (3/4)*(-2) = -3/2.
enlargement of scale -3/2 about the origin — matrix=[-3/2, 0; 0, -3/2]. enlargement of scale -3/2 about the origin — images of vertices 1,2,3=[-15/2, -3/2; 3/2, -9; 0, 3]. enlargement of scale 3/4 about the origin — matrix=[3/4, 0; 0, 3/4]. enlargement of scale 3/4 about the origin — images of vertices 1,2,3=[15/4, 3/4; -3/4, 9/2; 0, -3/2]. Review graph placement, axes, angle/direction, centre, reflection line and scale factor. General-angle irrational entries are taught but need a separate exact-surds or reviewed numerical interface.
Look for these in your work
- I retain the original matrices,labels and requested order.
- My working operands,intermediate values and matrix constructions are explicit.
- My separate final answers do not replace my working.
- I review the dimensions,units and any written or geometric argument with the stated limitations.
Common mistakes
- Scaling only one coordinate.
- Dropping the negative sign.
- Describing a negative scale only as a change in size.
- Using a non-origin centre while keeping the matrix kI₂.
What can you explain now?
Under scale−3/2 about the origin,what happens to distance and ray direction?
Compare with the explanation
Distance is multiplied by3/2 and the ray direction is reversed.
The signed scale determines direction,while its absolute value determines the distance multiplier.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Reconstruct the method from the original givens,justify every matrix order,retain all signed entries,and explain the result in its original labels,units or geometry. A fixed numerical comparison does not establish a written argument,mastery,specialist approval or formal assessment readiness.
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.