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\includegraphics[max width=\textwidth, alt={}, center]{7f66531c-2de6-44b7-9c48-7944acfea4d9-2_439_787_1174_678}
The diagram shows a semicircle \(A B C\) with centre \(O\) and radius 6 cm . The point \(B\) is such that angle \(B O A\) is \(90 ^ { \circ }\) and \(B D\) is an arc of a circle with centre \(A\). Find
- the length of the \(\operatorname { arc } B D\),
- the area of the shaded region.