(a)[1]
State the measure of angle $ACO$ in radians.
(b)[1]
Find $R$ in terms of $r$.
(c)[7]
Find the area of the shaded region in terms of $r$.
Mathematics 9709 · AS & A Level · Circular measure
Circular measure — practice question
In the diagram, points $A$, $B$ and $C$ are on a circle with centre $O$ and radius $r$. The angle $AOB$ measures $2.8$ radians. The shaded region has two arc boundaries. Its upper boundary is an arc from the circle centred at $O$ with radius $r$. Its lower boundary is an arc from a circle centred at $C$ with radius $R$.