(a)
Let $f(\theta) = \log\left( \frac{2 - \sin\theta}{2 + \sin\theta} \right)$
Now, $f( - \theta = \log\left( \frac{2 + \sin\theta}{2 - \sin\theta} \right)$
$= - \log\left( \frac{2 - \sin\theta}{2 + \sin\theta} \right) = - f(\theta)$
$\therefore f(\theta)$is an odd function.
So, $\int_{- \pi/2}^{\pi/2}{\log{\left( \frac{2 - \sin\theta}{2 + \sin\theta} \right)d\theta = 0}}$