Cosine of Full Angle

Theorem

 * $\cos 360^\circ = \cos 2 \pi = 1$

where $\cos$ denotes cosine and $360^\circ = 2 \pi$ is the full angle.

Proof
A direct implementation of Cosine of Multiple of Pi:
 * $\forall n \in \Z: \cos n \pi = \left({-1}\right)^n$

In this case, $n = 2$ and so:
 * $\sin 2 \pi = \left({-1}\right)^2 = 1$