6. A curve has polar equation \(r = a ( \cos \theta + 2 \sin \theta )\), where \(a\) is a positive constant and \(0 \leq \theta \leq \pi\).
- Determine the polar coordinates of the point on the curve which is furthest from the pole.
- Show that the curve is a circle whose radius should be specified.
- Write down the polar coordinates of the centre of the circle.
[0pt]
[BLANK PAGE]