2
\includegraphics[max width=\textwidth, alt={}, center]{5eb35648-db3f-4f29-b835-1aff4ef927b9-2_624_588_395_776} In the diagram, \(A Y B\) is a semicircle with \(A B\) as diameter and \(O A X B\) is a sector of a circle with centre \(O\) and radius \(r\). Angle \(A O B = 2 \theta\) radians. Find an expression, in terms of \(r\) and \(\theta\), for the area of the shaded region.