9231 P12 - Jun 2022 - Q06
4237
The curve C has polar equation \(r^2 = \arctan\left(\frac{1}{2}\theta\right)\), where \(0 \leq \theta \leq 2\).
(a) Sketch C and state, in exact form, the greatest distance of a point on C from the pole.
(b) Find the exact value of the area of the region bounded by C and the half-line \(\theta = 2\).
Now consider the part of C where \(0 \leq \theta \leq \frac{1}{2}\pi\).
(c) Show that, at the point furthest from the half-line \(\theta = \frac{1}{2}\pi\),
\((\theta^2 + 4)\arctan\left(\frac{1}{2}\theta\right)\sin\theta - \cos\theta = 0\)
and verify that this equation has a root between 0.6 and 0.7.
