Edexcel F2 2021 January — Question 7

Exam BoardEdexcel
ModuleF2 (Further Pure Mathematics 2)
Year2021
SessionJanuary
TopicPolar coordinates

7. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{4d3e1c8e-c659-4cfe-82ac-5bfce0f58ba3-24_445_597_248_676} \captionsetup{labelformat=empty} \caption{Figure 1}
\end{figure} Figure 1 shows a sketch of curve \(C\) with polar equation $$r = 3 \sin 2 \theta \quad 0 \leqslant \theta \leqslant \frac { \pi } { 2 }$$ The point \(P\) on \(C\) has polar coordinates \(( R , \phi )\). The tangent to \(C\) at \(P\) is perpendicular to the initial line.
  1. Show that \(\tan \phi = \frac { 1 } { \sqrt { 2 } }\)
  2. Determine the exact value of \(R\). The region \(S\), shown shaded in Figure 1, is bounded by \(C\) and the line \(O P\), where \(O\) is the pole.
  3. Use calculus to show that the exact area of \(S\) is $$p \arctan \frac { 1 } { \sqrt { 2 } } + q \sqrt { 2 }$$ where \(p\) and \(q\) are constants to be determined. Solutions relying entirely on calculator technology are not acceptable.