The reciprocal identity of $\csc \theta$ is $\frac{1}{\sin \theta}$ and the reciprocal identity of $\sec \theta$ is $\frac{1}{\cos \theta}$. So, the expression becomes:
$$
\sin ^{2} \theta \cdot \frac{1}{\sin \theta} \cdot \frac{1}{\cos \theta}
$$
Show more…