OCR FP1 2014 June — Question 4 6 marks

Exam BoardOCR
ModuleFP1 (Further Pure Mathematics 1)
Year2014
SessionJune
Marks6
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicLinear transformations
TypeWrite down transformation matrix
DifficultyModerate -0.3 This is a standard Further Maths FP1 question on matrix transformations requiring routine recognition of shear and rotation matrices. Part (a) involves direct application of shear formula, part (b)(i) requires recognizing a rotation matrix from its form (cos/sin pattern), and part (b)(ii) is straightforward determinant calculation with standard interpretation. While this is Further Maths content, these are textbook exercises with no problem-solving or novel insight required, making it slightly easier than average overall.
Spec4.03d Linear transformations 2D: reflection, rotation, enlargement, shear4.03h Determinant 2x2: calculation4.03i Determinant: area scale factor and orientation

4
  1. Find the matrix that represents a shear with the \(y\)-axis invariant, the image of the point \(( 1,0 )\) being the point \(( 1,4 )\).
  2. The matrix \(\mathbf { X }\) is given by \(\mathbf { X } = \left( \begin{array} { r r } \frac { 1 } { 2 } \sqrt { 2 } & \frac { 1 } { 2 } \sqrt { 2 } \\ - \frac { 1 } { 2 } \sqrt { 2 } & \frac { 1 } { 2 } \sqrt { 2 } \end{array} \right)\).
    1. Describe fully the geometrical transformation represented by \(\mathbf { X }\).
    2. Find the value of the determinant of \(\mathbf { X }\) and describe briefly how this value relates to the transformation represented by \(\mathbf { X }\).

Question 4(a):
AnswerMarks Guidance
AnswerMarks Guidance
\(\begin{pmatrix}1 & 0\\4 & 1\end{pmatrix}\) — each column correctB1 B1
[2]
Question 4(b)(i):
AnswerMarks Guidance
AnswerMarks Guidance
Rotation, \(45°\) or \(\pi/4\) clockwise or equivalentB1 B1 Must be rotation and no other transformation, otherwise 0/2
[2]
Question 4(b)(ii):
AnswerMarks Guidance
AnswerMarks Guidance
\((\det \mathbf{X} =) 1\) — correct valueB1
Scale factor for area or equivalentB1ft e.g. area unchanged
[2]
# Question 4(a):
| Answer | Marks | Guidance |
|--------|-------|----------|
| $\begin{pmatrix}1 & 0\\4 & 1\end{pmatrix}$ — each column correct | B1 B1 | |
| **[2]** | | |

---

# Question 4(b)(i):
| Answer | Marks | Guidance |
|--------|-------|----------|
| Rotation, $45°$ or $\pi/4$ clockwise or equivalent | B1 B1 | Must be rotation and no other transformation, otherwise 0/2 |
| **[2]** | | |

---

# Question 4(b)(ii):
| Answer | Marks | Guidance |
|--------|-------|----------|
| $(\det \mathbf{X} =) 1$ — correct value | B1 | |
| Scale factor for **area** or equivalent | B1ft | e.g. area unchanged |
| **[2]** | | |

---
4
\begin{enumerate}[label=(\alph*)]
\item Find the matrix that represents a shear with the $y$-axis invariant, the image of the point $( 1,0 )$ being the point $( 1,4 )$.
\item The matrix $\mathbf { X }$ is given by $\mathbf { X } = \left( \begin{array} { r r } \frac { 1 } { 2 } \sqrt { 2 } & \frac { 1 } { 2 } \sqrt { 2 } \\ - \frac { 1 } { 2 } \sqrt { 2 } & \frac { 1 } { 2 } \sqrt { 2 } \end{array} \right)$.
\begin{enumerate}[label=(\roman*)]
\item Describe fully the geometrical transformation represented by $\mathbf { X }$.
\item Find the value of the determinant of $\mathbf { X }$ and describe briefly how this value relates to the transformation represented by $\mathbf { X }$.
\end{enumerate}\end{enumerate}

\hfill \mbox{\textit{OCR FP1 2014 Q4 [6]}}