Problem

The diagram shows a triangle $OAB$ where $OA = OB = 10$ cm and angle $AOB = 0.8$ radians. Points $C$ and $D$ on $OA$ and $OB$ respectively are such that the arc $CD$ is part of a circle with centre $O$ and radius 6 cm. The shaded region is bounded by the arc $CD$ and the line segments $CA$, $AB$ and $BD$.

(a) Find the perimeter of the shaded region.

(b) Find the area of the shaded region.