4 The part of the curve \(y = 4 - x ^ { 2 }\) that is above the \(x\)-axis is rotated about the \(y\)-axis. This is shown in Fig. 4.
Find the volume of revolution produced, giving your answer in terms of \(\pi\).
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{8d786d33-c5c2-44a6-8273-7a3e43e552ef-3_534_595_1831_785}
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\caption{Fig. 4}
\end{figure}