Jul 28, 2016

Not sure what the question is but
if it is to identify the "excluded values"
then $x \notin \left\{k \cdot \pi | k \in \mathbb{Z}\right\}$

#### Explanation:

Since the function definition requires division by $\sin x$
then $\sin x \ne 0$
$\rightarrow x \ne k \cdot \pi$ for any $k \in \mathbb{Z}$

Note that if $k$ is an odd integer
the function evaluates as a removable discontinuity.