(c)
$\lim_{x \rightarrow \pi}\ \frac{(1 + \cos{x) - \sin x}}{(1 + \cos{x) + \sin x}}\$
$= \lim_{x \rightarrow \pi}\frac{2\cos^{2}{x/2 - 2(\sin{x/2)\ cos\ x/2}}}{2\cos^{2}{x/2 + 2(\sin{x/2)\ cos\ x/2}}}$
$= \lim_{x \rightarrow \pi}\tan{\left( \frac{\pi}{4} - \frac{\pi}{2} \right) = - 1}$
Since, $f(x)$ is continuous at $x = \pi$
$\therefore\ \ f(\pi) = \lim_{x \rightarrow \pi}\ f(x) = - 1$