3
\includegraphics[max width=\textwidth, alt={}, center]{d0074ac8-42d2-49f4-a417-4a348537bccc-2_492_682_708_733} In the diagram, \(O A B\) is a sector of a circle with centre \(O\) and radius 8 cm . Angle \(B O A\) is \(\alpha\) radians. \(O A C\) is a semicircle with diameter \(O A\). The area of the semicircle \(O A C\) is twice the area of the sector \(O A B\).

1. Find \(\alpha\) in terms of \(\pi\).
2. Find the perimeter of the complete figure in terms of \(\pi\).