4 Fig. 4 shows the curve \(y = \mathrm { f } ( x )\), where \(\mathrm { f } ( x ) = \sqrt { 1 - 9 x ^ { 2 } } , - a \leqslant x \leqslant a\).
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{7b77c646-2bc5-4166-b22e-3c1229abd722-2_476_572_861_751}
\captionsetup{labelformat=empty}
\caption{Fig. 4}
\end{figure}
- Find the value of \(a\).
- Write down the range of \(\mathrm { f } ( x )\).
- Sketch the curve \(y = \mathrm { f } \left( \frac { 1 } { 3 } x \right) - 1\).