4 Functions f and g are defined by
$$\begin{aligned}
& \mathrm { f } : x \mapsto 2 - 3 \cos x \quad \text { for } 0 \leqslant x \leqslant 2 \pi
& \mathrm {~g} : x \mapsto \frac { 1 } { 2 } x \quad \text { for } 0 \leqslant x \leqslant 2 \pi
\end{aligned}$$
- Solve the equation \(\operatorname { fg } ( x ) = 1\).
- Sketch the graph of \(y = \mathrm { f } ( x )\).