4 The variables \(x\) and \(y\) satisfy the differential equation
$$( 1 - \cos x ) \frac { \mathrm { d } y } { \mathrm {~d} x } = y \sin x$$
It is given that \(y = 4\) when \(x = \pi\).
- Solve the differential equation, obtaining an expression for \(y\) in terms of \(x\).
- Sketch the graph of \(y\) against \(x\) for \(0 < x < 2 \pi\).