Let $\sin$ be the D1931: Standard real sine function.
Let $\pi$ be the D168: Pi.
The standard real cosecant function is the D4364: Real function \begin{equation} \csc : \mathbb{R} \setminus \{ \pi n : n \in \mathbb{Z} \} \to (-\infty, -1] \cup [1, \infty), \quad \csc(x) = \frac{1}{\sin(x)} \end{equation}