Sine of Straight Angle

Theorem

 * $\sin 180^\circ = \sin \pi = 0$

where $\sin$ denotes the sine function.

Proof
A direct implementation of Sine of Multiple of Pi:
 * $\forall n \in \Z: \sin n \pi = 0$

In this case, $n = 0$ and so:
 * $\sin \pi = 0$