Cosecant of Zero

Theorem

 * $\csc 0$ is undefined

where $\csc$ denotes cosecant.

Proof
From Cosecant is Reciprocal of Sine:
 * $\csc \theta = \dfrac 1 {\sin \theta}$

From Sine of Zero is Zero:
 * $\sin 0 = 0$

Thus $\csc \theta$ is undefined at this value.