Edexcel C4 — Question 6

Exam BoardEdexcel
ModuleC4 (Core Mathematics 4)
TopicArea Under & Between Curves

6. \begin{figure}[h]
\captionsetup{labelformat=empty} \caption{Figure 2} \includegraphics[alt={},max width=\textwidth]{07bc7f2d-c2b9-4502-91cd-a76afb1ca6c0-5_809_1226_201_303}
\end{figure} Figure 2 shows the cross-section of a road tunnel and its concrete surround. The curved section of the tunnel is modelled by the curve with equation \(y = 8 \sqrt { \left( \sin \frac { \pi x } { 10 } \right) }\), in the interval \(0 \leq x \leq\) 10. The concrete surround is represented by the shaded area bounded by the curve, the \(x\)-axis and the lines \(x = - 2 , x = 12\) and \(y = 10\). The units on both axes are metres.
  1. Using this model, copy and complete the table below, giving the values of \(y\) to 2 decimal places.
    \(x\)0246810
    \(y\)06.130
    The area of the cross-section of the tunnel is given by \(\int _ { 0 } ^ { 10 } y \mathrm {~d} x\).
  2. Estimate this area, using the trapezium rule with all the values from your table.
  3. Deduce an estimate of the cross-sectional area of the concrete surround.
  4. State, with a reason, whether your answer in part (c) over-estimates or under-estimates the true value.
    (2)