3
\includegraphics[max width=\textwidth, alt={}, center]{d6976a4b-aecf-43f1-a3f2-bcad37d03585-05_483_561_287_753} The diagram shows a sector of a circle with centre \(C\). The radii \(C A\) and \(C B\) each have length \(r \mathrm {~cm}\) and the size of the reflex angle \(A C B\) is \(\theta\) radians. The sector, shaded in the diagram, has a perimeter of 65 cm and an area of \(225 \mathrm {~cm} ^ { 2 }\).

1. Find the values of \(r\) and \(\theta\).
2. Find the area of triangle \(A C B\).