OCR C2 — Question 6 8 marks

Exam BoardOCR
ModuleC2 (Core Mathematics 2)
Marks8
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicTrig Graphs & Exact Values
TypeSketch single standard trig graph (sin/cos/tan)
DifficultyModerate -0.8 This is a straightforward C2 trigonometry question requiring a standard sketch of cos(2x), identifying intercepts by inspection (x-intercepts at π/4, 3π/4 where cos(2x)=0, y-intercept at (0,1)), and solving a basic equation cos(2x)=0.5 using inverse cosine. All parts are routine recall and application of standard techniques with no problem-solving insight required, making it easier than average.
Spec1.05f Trigonometric function graphs: symmetries and periodicities1.05o Trigonometric equations: solve in given intervals

$$f(x) = \cos 2x, \quad 0 \leq x \leq \pi.$$
  1. Sketch the curve \(y = f(x)\). [2]
  2. Write down the coordinates of any points where the curve \(y = f(x)\) meets the coordinate axes. [3]
  3. Solve the equation \(f(x) = 0.5\), giving your answers in terms of \(\pi\). [3]

(i)
AnswerMarks
Graph of curve with correct shape showing one complete oscillation with maximum at originB2
(ii)
AnswerMarks
\((0, 1), (\frac{\pi}{2}, 0), (\frac{3\pi}{4}, 0)\)B3
(iii)
\(\cos 2x = 0.5\)
\(2x = \frac{\pi}{3}, 2\pi - \frac{\pi}{3}\)
\(2x = \frac{\pi}{3}, \frac{5\pi}{3}\)
AnswerMarks Guidance
\(x = \frac{\pi}{6}, \frac{5\pi}{6}\)B1 M1 A1
## (i)
Graph of curve with correct shape showing one complete oscillation with maximum at origin | B2 |

## (ii)
$(0, 1), (\frac{\pi}{2}, 0), (\frac{3\pi}{4}, 0)$ | B3 |

## (iii)
$\cos 2x = 0.5$
$2x = \frac{\pi}{3}, 2\pi - \frac{\pi}{3}$
$2x = \frac{\pi}{3}, \frac{5\pi}{3}$
$x = \frac{\pi}{6}, \frac{5\pi}{6}$ | B1 M1 | A1 | (8)

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$$f(x) = \cos 2x, \quad 0 \leq x \leq \pi.$$

\begin{enumerate}[label=(\roman*)]
\item Sketch the curve $y = f(x)$. [2]
\item Write down the coordinates of any points where the curve $y = f(x)$ meets the coordinate axes. [3]
\item Solve the equation $f(x) = 0.5$, giving your answers in terms of $\pi$. [3]
\end{enumerate}

\hfill \mbox{\textit{OCR C2  Q6 [8]}}