(a) Separate variables:

\(\frac{dy}{y} = \frac{\sin x}{1 - \cos x} dx\)

Integrate both sides:

\(\int \frac{dy}{y} = \int \frac{\sin x}{1 - \cos x} dx\)

\(\ln y = -\ln(1 - \cos x) + C\)

\(\ln y = \ln(1 - \cos x)^{-1} + C\)

\(y = e^C (1 - \cos x)^{-1}\)

Use initial condition \(y = 4\) when \(x = \pi\):

\(4 = e^C (1 - \cos \pi)^{-1}\)

\(4 = e^C (1 - (-1))^{-1}\)

\(4 = e^C \cdot \frac{1}{2}\)

\(e^C = 8\)

Thus, \(y = 8(1 - \cos x)^{-1}\)

\(y = 2(1 - \cos x)\)

(b) The graph of \(y = 2(1 - \cos x)\) is a sinusoidal curve with a maximum at \(x = \pi\) for \(0 < x < 2\pi\).