4. The curve \(C\) has polar equation \(\quad r = 6 \cos \theta , \quad - \frac { \pi } { 2 } \leq \theta < \frac { \pi } { 2 }\), and the line \(D\) has polar equation \(\quad r = 3 \sec \left( \frac { \pi } { 3 } - \theta \right) , \quad - \frac { \pi } { 6 } < \theta < \frac { 5 \pi } { 6 }\).
- Find a cartesian equation of \(C\) and a cartesian equation of \(D\).
- Sketch on the same diagram the graphs of \(C\) and \(D\), indicating where each cuts the initial line.
The graphs of \(C\) and \(D\) intersect at the points \(P\) and \(Q\).
- Find the polar coordinates of \(P\) and \(Q\).
(5)(Total 13 marks)