(a)[2]
Show that the result is $s=\sqrt{3}r$.
(b)[7]
Find an expression for the area of the shaded region. Give your answer in the form $(a + b\pi)r^2$, where $a$ and $b$ are constants to be found.
Mathematics 9709 · AS & A Level · Circular measure
Circular measure — practice question
The diagram contains a circle centred at A with radius $r$ that passes through B, C and D. There is also a larger circle, with centre C and radius $s$, which passes through B and D. Also, the length $BD$ is $s$.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Set up the correct equation, for example $s^2=r^2+r^2-2r^2\cos\frac{2\pi}{3}$” …
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