Mathematics
Grade 12
15 min
Transformation matrices write the vertex matrix
Transformation matrices write the vertex matrix
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Define a vertex matrix and describe its standard structure.
Represent any 2D polygon as a 2xn vertex matrix.
Construct a vertex matrix from a given list of coordinates.
Extract vertex coordinates from a polygon on a Cartesian plane and write the corresponding vertex matrix.
Explain why a vertex matrix must have 2 rows for 2D transformations.
Predict the dimensions of a vertex matrix for a polygon with 'n' vertices.
Ever wonder how animators make characters move and change shape on screen? 🎬 It all starts with representing the character as a set of points that can be manipulated with matrix mathematics!
This tutorial focuses on the foundational first step of geometric transformations: correctly representing a 2D shape as a 'vertex matrix&#...
2
Key Concepts & Vocabulary
TermDefinitionExample
VertexA point where two or more lines, curves, or edges meet. In the context of polygons, a vertex is a corner.A triangle with vertices at (1, 2), (3, 4), and (5, 1) has three corners, which are its vertices.
PolygonA closed two-dimensional figure made up of straight line segments.Triangles, quadrilaterals, pentagons, and hexagons are all polygons.
Vertex MatrixA matrix where each column represents a vertex of a polygon. For 2D shapes, the first row contains the x-coordinates and the second row contains the y-coordinates.For a triangle with vertices A(1,5), B(2,8), and C(3,4), the vertex matrix is [[1, 2, 3], [5, 8, 4]].
Pre-imageThe original geometric figure before a transformation is applied.The initial triangle defined by a vertex matrix is the pre-image.
ImageThe...
3
Core Formulas
Standard Vertex Matrix Structure
V = \begin{bmatrix} x_1 & x_2 & \dots & x_n \\ y_1 & y_2 & \dots & y_n \end{bmatrix}
For a polygon with 'n' vertices (x₁, y₁), (x₂, y₂), ..., (xₙ, yₙ), the vertex matrix V is a 2xn matrix. The top row always contains the x-coordinates and the bottom row always contains the y-coordinates. Each column corresponds to one vertex.
Transformation Equation
V' = T \cdot V
The image matrix (V') is found by multiplying the transformation matrix (T) by the pre-image vertex matrix (V). For this multiplication to be possible with a 2x2 transformation matrix T, the vertex matrix V must have 2 rows.
4 more steps in this tutorial
Sign up free to access the complete tutorial with worked examples and practice.
Sign Up Free to ContinueSample Practice Questions
Challenging
A regular hexagon is centered at the origin, and one of its vertices is at (6, 0). Which of the following columns could NOT represent another vertex in its vertex matrix?
A.\begin{bmatrix} 3 \ 3\sqrt{3} \end{bmatrix}
B.\begin{bmatrix} -3 \ 3\sqrt{3} \end{bmatrix}
C.\begin{bmatrix} -6 \ 0 \end{bmatrix}
D.\begin{bmatrix} 6 \ -6 \end{bmatrix}
Challenging
A vertex matrix V = \begin{bmatrix} x_1 & x_2 & x_3 \ y_1 & y_2 & y_3 \end{bmatrix} represents a triangle. A new matrix V_new is formed by swapping the first and second rows of V. Geometrically, what does V_new represent?
A.reflection of the original triangle across the line y = x.
B.rotation of the original triangle by 90 degrees.
C.triangle with vertices (y_1, x_1), (y_2, x_2), (y_3, x_3).
D.An invalid polygon as the matrix structure is now incorrect.
Challenging
The vertex matrix for a polygon is V. A new matrix V_T is created by adding 4 to every element in the first row of V and subtracting 2 from every element in the second row. This corresponds to what geometric transformation?
A.dilation by a factor of 4 in the x-direction and -2 in the y-direction.
B.translation of 4 units right and 2 units down.
C.shear transformation.
D.rotation followed by a translation.
Want to practice and check your answers?
Sign up to access all questions with instant feedback, explanations, and progress tracking.
Start Practicing Free