A new design for a company logo is to be made from two sectors of a circle, \(ORP\) and \(OQS\), and a rhombus \(OSTR\), as shown in the diagram below.
\includegraphics{figure_7}
The points \(P\), \(O\) and \(Q\) lie on a straight line and the angle \(ROS\) is \(\theta\) radians.
A large copy of the logo, with \(PQ = 5\) metres, is to be put on a wall.
- Show that the area of the logo, \(A\) square metres, is given by
$$A = \frac{25}{8}(\pi - \theta + 2\sin\theta)$$
[4 marks]
- Show that the maximum value of \(A\) occurs when \(\theta = \frac{\pi}{3}\)
Fully justify your answer.
[6 marks]
- Find the exact maximum value of \(A\)
[2 marks]
- Without further calculation, state how your answers to parts (b)(i) and (b)(ii) would change if \(PQ\) were increased to 10 metres.
[2 marks]