Let $\sin$ be the D1931: Standard real sine function.
Let $\cos$ be the D1927: Standard real cosine function.
The standard real cotangent function is the D4364: Real function \begin{equation} \cot : \mathbb{R} \setminus \left\{ n \pi : n \in \mathbb{Z} \right\} \to \mathbb{R}, \quad \cot(x) = \frac{\cos(x)}{\sin(x)} \end{equation}