Answer
See the explanation below.
Work Step by Step
$\frac{1-\cos \theta }{\sin \theta }=\csc \theta -\cot \theta $
Recall Trigonometric Identities,
$\begin{align}
& \cot \theta =\frac{\cos \theta }{\sin \theta } \\
& \csc \theta =\frac{1}{\sin \theta } \\
\end{align}$
Use the above identities and solve the left side of the given expression,
$\begin{align}
& \frac{1-\cos \theta }{\sin \theta }=\frac{1}{\sin \theta }-\frac{cos\theta }{\sin \theta } \\
& =\csc \theta -\cot \theta
\end{align}$
Therefore,
$\frac{1-\cos \theta }{\sin \theta }=\csc \theta -\cot \theta $
