# Nakafa Framework: LLM

URL: /en/subject/high-school/11/mathematics/geometric-transformation/dilation-matrix
Source: https://raw.githubusercontent.com/nakafaai/nakafa.com/refs/heads/main/packages/contents/subject/high-school/11/mathematics/geometric-transformation/dilation-matrix/en.mdx

Output docs content for large language models.

---

import { getColor } from "@repo/design-system/lib/color";
import { LineEquation } from "@repo/design-system/components/contents/line-equation";

export const metadata = {
  title: "Dilation Matrix",
  description: "Discover how to represent dilation using matrices. Learn matrix operations for scaling shapes from origin and arbitrary points with worked examples.",
  authors: [{ name: "Nabil Akbarazzima Fatih" }],
  date: "05/10/2025",
  subject: "Geometric Transformation",
};

## Finding the Matrix Associated with Dilation

How to find the matrix associated with a dilation operation? Recall that a point <InlineMath math="(x,y)" /> is mapped by a dilation with a factor <InlineMath math="k \neq 0" /> and center <InlineMath math="O" /> to <InlineMath math="(kx,ky)" />.

Suppose the matrix we are looking for is <InlineMath math="\begin{pmatrix} r & s \\ t & u \end{pmatrix}" />.

Find <InlineMath math="r, s, t, u" /> such that it satisfies

<BlockMath math="\begin{pmatrix} r & s \\ t & u \end{pmatrix} \begin{pmatrix} x \\ y \end{pmatrix} = \begin{pmatrix} kx \\ ky \end{pmatrix}" />

From the matrix multiplication on the left side, we get:

<BlockMath math="\begin{pmatrix} rx + sy \\ tx + uy \end{pmatrix} = \begin{pmatrix} kx \\ ky \end{pmatrix}" />

By equating the corresponding components:

- **First row:** <InlineMath math="rx + sy = kx" />. For this equation to hold for all <InlineMath math="x" /> and <InlineMath math="y" />, the coefficients of <InlineMath math="x" /> must be equal, and the coefficients of <InlineMath math="y" /> must be equal. Thus, <InlineMath math="r = k" /> and <InlineMath math="s = 0" />.
- **Second row:** <InlineMath math="tx + uy = ky" />. Similarly, <InlineMath math="t = 0" /> and <InlineMath math="u = k" />.

## Dilation Matrix with Respect to the Origin

The matrix associated with a dilation by a factor <InlineMath math="k \neq 0" /> with respect to the origin <InlineMath math="O(0,0)" /> is

<BlockMath math="\begin{pmatrix} k & 0 \\ 0 & k \end{pmatrix}" />

## Matrix Operation for Dilation with Respect to an Arbitrary Point

A point <InlineMath math="(x,y)" /> dilated by a factor <InlineMath math="k \neq 0" /> and center <InlineMath math="(a,b)" /> will be mapped to <InlineMath math="(k(x-a)+a,\, k(y-b)+b)" />.

Find the combination of matrix operations on the position vector <InlineMath math="\begin{pmatrix} x-a \\ y-b \end{pmatrix}" /> such that the result is <InlineMath math="\begin{pmatrix} k(x-a)+a \\ k(y-b)+b \end{pmatrix}" />.

The matrix operation associated with a dilation by a factor <InlineMath math="k \neq 0" /> with respect to the point <InlineMath math="(a,b)" /> is

<BlockMath math="\begin{pmatrix} x' \\ y' \end{pmatrix} = \begin{pmatrix} k & 0 \\ 0 & k \end{pmatrix} \begin{pmatrix} x-a \\ y-b \end{pmatrix} + \begin{pmatrix} a \\ b \end{pmatrix}" />

or it can also be written as:

<BlockMath math="\begin{pmatrix} x' \\ y' \end{pmatrix} - \begin{pmatrix} a \\ b \end{pmatrix} = \begin{pmatrix} k & 0 \\ 0 & k \end{pmatrix} \left( \begin{pmatrix} x \\ y \end{pmatrix} - \begin{pmatrix} a \\ b \end{pmatrix} \right)" />

## Finding the Image of a Dilation Using Matrices

Determine the image of point <InlineMath math="A(2,4)" /> transformed by a dilation with a factor of <InlineMath math="2" /> with respect to the center point <InlineMath math="P(1,1)" />!

**Alternative Solution:**

Given <InlineMath math="x=2, y=4, k=2, a=1, b=1" />.

<div className="flex flex-col gap-4">
  <BlockMath math="\begin{pmatrix} x' \\ y' \end{pmatrix} = \begin{pmatrix} 2 & 0 \\ 0 & 2 \end{pmatrix} \begin{pmatrix} 2-1 \\ 4-1 \end{pmatrix} + \begin{pmatrix} 1 \\ 1 \end{pmatrix}" />
  <BlockMath math="\begin{pmatrix} x' \\ y' \end{pmatrix} = \begin{pmatrix} 2 & 0 \\ 0 & 2 \end{pmatrix} \begin{pmatrix} 1 \\ 3 \end{pmatrix} + \begin{pmatrix} 1 \\ 1 \end{pmatrix}" />
  <BlockMath math="\begin{pmatrix} x' \\ y' \end{pmatrix} = \begin{pmatrix} (2)(1) + (0)(3) \\ (0)(1) + (2)(3) \end{pmatrix} + \begin{pmatrix} 1 \\ 1 \end{pmatrix}" />
  <BlockMath math="\begin{pmatrix} x' \\ y' \end{pmatrix} = \begin{pmatrix} 2 \\ 6 \end{pmatrix} + \begin{pmatrix} 1 \\ 1 \end{pmatrix} = \begin{pmatrix} 3 \\ 7 \end{pmatrix}" />
</div>

Thus, the image of point <InlineMath math="A(2,4)" /> is <InlineMath math="A'(3,7)" />.

<LineEquation
  title={
    <>
      Visualization of Dilation of Point <InlineMath math="A(2,4)" /> with
      Center <InlineMath math="P(1,1)" /> and Scale Factor{" "}
      <InlineMath math="k=2" />
    </>
  }
  description={
    <>
      Point <InlineMath math="A(2,4)" /> is dilated with respect to the center{" "}
      <InlineMath math="P(1,1)" /> with a scale factor <InlineMath math="k=2" />{" "}
      to produce the image <InlineMath math="A'(3,7)" />. The line from the
      center to the original point and from the center to the image lie on the
      same line, and the distance <InlineMath math="PA'" /> is twice the
      distance <InlineMath math="PA" />.
    </>
  }
  data={[
    {
      points: [{ x: 1, y: 1, z: 0 }],
      color: getColor("ROSE"),
      showPoints: true,
      labels: [{ text: "P(1,1)", at: 0, offset: [-0.5, -0.5, 0] }],
    },
    {
      points: [{ x: 2, y: 4, z: 0 }],
      color: getColor("SKY"),
      showPoints: true,
      labels: [{ text: "A(2,4)", at: 0, offset: [1.5, 0.2, 0] }],
    },
    {
      points: [{ x: 3, y: 7, z: 0 }],
      color: getColor("EMERALD"),
      showPoints: true,
      labels: [{ text: "A'(3,7)", at: 0, offset: [0.5, 0.5, 0] }],
    },
    {
      points: [
        { x: 1, y: 1, z: 0 }, // P
        { x: 2, y: 4, z: 0 }, // A
      ],
      color: getColor("AMBER"),
    },
    {
      points: [
        { x: 1, y: 1, z: 0 }, // P
        { x: 3, y: 7, z: 0 }, // A'
      ],
      color: getColor("SKY"),
      cone: { position: "end", size: 0.3 },
    },
  ]}
  showZAxis={false}
  cameraPosition={[0, 0, 18]}
/>

## Exercises

1.  Find the coordinates of the image of the point <InlineMath math="(a,b)" /> under the dilation <InlineMath math="[O,3]" />!
2.  Determine the matrix corresponding to a dilation with a scale factor of <InlineMath math="-2" /> and centered at <InlineMath math="O(0,0)" />.
3.  A point <InlineMath math="B(-1, 5)" /> is dilated with center <InlineMath math="P(2, -3)" /> and scale factor <InlineMath math="k = \frac{1}{2}" />. Determine the coordinates of the image of point <InlineMath math="B" />!
4.  A triangle <InlineMath math="KLM" /> with vertices <InlineMath math="K(1,1)" />, <InlineMath math="L(5,1)" />, and <InlineMath math="M(3,4)" /> is dilated with center <InlineMath math="O(0,0)" /> and scale factor <InlineMath math="2" />. Draw the original triangle and its image, then determine the coordinates of the image vertices!

### Key Answers

1. The dilation <InlineMath math="[O,3]" /> means the center of dilation is <InlineMath math="O(0,0)" /> and the scale factor is <InlineMath math="k=3" />.

   Let the point be <InlineMath math="Q(a,b)" />.

   Then <InlineMath math="x=a, y=b, k=3" />.

   <BlockMath math="\begin{pmatrix} x' \\ y' \end{pmatrix} = \begin{pmatrix} 3 & 0 \\ 0 & 3 \end{pmatrix} \begin{pmatrix} a \\ b \end{pmatrix} = \begin{pmatrix} 3a \\ 3b \end{pmatrix}" />

   Thus, the coordinates of the image of point <InlineMath math="(a,b)" /> are <InlineMath math="(3a, 3b)" />.

2. Scale factor <InlineMath math="k=-2" />, center <InlineMath math="O(0,0)" />.

   The dilation matrix is:

   <BlockMath math="\begin{pmatrix} -2 & 0 \\ 0 & -2 \end{pmatrix}" />.

3. Point <InlineMath math="B(-1, 5)" />, center <InlineMath math="P(2, -3)" />, scale factor <InlineMath math="k = \frac{1}{2}" />.

   <InlineMath math="x=-1, y=5, a=2, b=-3, k=\frac{1}{2}" />.

   <div className="flex flex-col gap-4">
     <BlockMath math="\begin{pmatrix} x' \\ y' \end{pmatrix} = \begin{pmatrix} \frac{1}{2} & 0 \\ 0 & \frac{1}{2} \end{pmatrix} \begin{pmatrix} -1-2 \\ 5-(-3) \end{pmatrix} + \begin{pmatrix} 2 \\ -3 \end{pmatrix}" />
     <BlockMath math="\begin{pmatrix} x' \\ y' \end{pmatrix} = \begin{pmatrix} \frac{1}{2} & 0 \\ 0 & \frac{1}{2} \end{pmatrix} \begin{pmatrix} -3 \\ 8 \end{pmatrix} + \begin{pmatrix} 2 \\ -3 \end{pmatrix}" />
     <BlockMath math="\begin{pmatrix} x' \\ y' \end{pmatrix} = \begin{pmatrix} (\frac{1}{2})(-3) + (0)(8) \\ (0)(-3) + (\frac{1}{2})(8) \end{pmatrix} + \begin{pmatrix} 2 \\ -3 \end{pmatrix}" />
     <BlockMath math="\begin{pmatrix} x' \\ y' \end{pmatrix} = \begin{pmatrix} -\frac{3}{2} \\ 4 \end{pmatrix} + \begin{pmatrix} 2 \\ -3 \end{pmatrix} = \begin{pmatrix} -\frac{3}{2} + \frac{4}{2} \\ 4 - 3 \end{pmatrix} = \begin{pmatrix} \frac{1}{2} \\ 1 \end{pmatrix}" />
   </div>

   The coordinates of the image of point <InlineMath math="B" /> are <InlineMath math="B'(\frac{1}{2}, 1)" />.

4. Triangle <InlineMath math="KLM" /> with <InlineMath math="K(1,1)" />, <InlineMath math="L(5,1)" />, <InlineMath math="M(3,4)" />.

   Center <InlineMath math="O(0,0)" />, <InlineMath math="k=2" />.

   Image of point <InlineMath math="K(1,1)" />:

   <BlockMath math="\begin{pmatrix} x_K' \\ y_K' \end{pmatrix} = \begin{pmatrix} 2 & 0 \\ 0 & 2 \end{pmatrix} \begin{pmatrix} 1 \\ 1 \end{pmatrix} = \begin{pmatrix} 2 \\ 2 \end{pmatrix} \implies K'(2,2)" />

   Image of point <InlineMath math="L(5,1)" />:

   <BlockMath math="\begin{pmatrix} x_L' \\ y_L' \end{pmatrix} = \begin{pmatrix} 2 & 0 \\ 0 & 2 \end{pmatrix} \begin{pmatrix} 5 \\ 1 \end{pmatrix} = \begin{pmatrix} 10 \\ 2 \end{pmatrix} \implies L'(10,2)" />

   Image of point <InlineMath math="M(3,4)" />:

   <div className="flex flex-col gap-4">
     <BlockMath math="\begin{pmatrix} x_M' \\ y_M' \end{pmatrix} = \begin{pmatrix} 2 & 0 \\ 0 & 2 \end{pmatrix} \begin{pmatrix} 3 \\ 4 \end{pmatrix} = \begin{pmatrix} 6 \\ 8 \end{pmatrix} \implies M'(6,8)" />
     <LineEquation
       title={
         <>
           Visualization of Dilation of Triangle <InlineMath math="KLM" /> with
           Center <InlineMath math="O(0,0)" /> and Scale Factor{" "}
           <InlineMath math="k=2" />
         </>
       }
       description={
         <>
           Triangle <InlineMath math="KLM" /> is dilated to become triangle{" "}
           <InlineMath math="K'L'M'" />. The center of dilation is{" "}
           <InlineMath math="O(0,0)" />.
         </>
       }
       data={[
         // Original Triangle KLM
         {
           points: [
             { x: 1, y: 1, z: 0 }, // K
             { x: 5, y: 1, z: 0 }, // L
           ],
           color: getColor("SKY"),
           labels: [
             { text: "K(1,1)", at: 0, offset: [-0.7, -0.2, 0] },
             { text: "L(5,1)", at: 1, offset: [0.7, -0.2, 0] },
           ],
           showPoints: true,
         },
         {
           points: [
             { x: 5, y: 1, z: 0 }, // L
             { x: 3, y: 4, z: 0 }, // M
           ],
           color: getColor("ORANGE"),
           labels: [{ text: "M(3,4)", at: 1, offset: [0, 0.5, 0] }],
           showPoints: true,
         },
         {
           points: [
             { x: 3, y: 4, z: 0 }, // M
             { x: 1, y: 1, z: 0 }, // K
           ],
           color: getColor("PURPLE"),
           showPoints: true,
         },
         // Dilated Triangle K'L'M'
         {
           points: [
             { x: 2, y: 2, z: 0 }, // K'
             { x: 10, y: 2, z: 0 }, // L'
           ],
           color: getColor("TEAL"),
           labels: [
             { text: "K'(2,2)", at: 0, offset: [-0.8, -0.3, 0] },
             { text: "L'(10,2)", at: 1, offset: [0.8, -0.3, 0] },
           ],
           showPoints: true,
         },
         {
           points: [
             { x: 10, y: 2, z: 0 }, // L'
             { x: 6, y: 8, z: 0 }, // M'
           ],
           color: getColor("PINK"),
           labels: [{ text: "M'(6,8)", at: 1, offset: [0, 0.6, 0] }],
           showPoints: true,
         },
         {
           points: [
             { x: 6, y: 8, z: 0 }, // M'
             { x: 2, y: 2, z: 0 }, // K'
           ],
           color: getColor("INDIGO"),
           showPoints: true,
         },
         // Origin
         {
           points: [{ x: 0, y: 0, z: 0 }],
           color: getColor("INDIGO"),
           showPoints: true,
           labels: [{ text: "O", at: 0, offset: [-0.3, -0.3, 0] }],
         },
       ]}
       showZAxis={false}
       cameraPosition={[0, 0, 20]}
     />
   </div>