In this question lengths are in centimetres. ![](https://cdn.mathpix.com/cropped/eeb31b4c-ef93-456c-8fd5-3a3909034666-06.jpg?height=427&width=428&top_left_y=298&top_left_x=244) The diagram shows a circle with centre \(O\) and radius \(r\). Points \(A, B\) and \(C\) are on the circumference of the circle. Angle \(A O B=\alpha\) radians. (a) The perimeter of the shaded sector is equal to the length of the major arc, \(A C B\). Find the exact value of \(\alpha\). (b) The area of the shaded sector is \(18\left(\pi^{2}-1\right)\). Find the exact value of \(r\). Simplify your answer.

2026 - M/J - 0606/12 | Q6

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In this question lengths are in centimetres. ![](https://...