Sinus

Die Definition lautet $\sin (x) = \frac{e^{x i} - e^{- x i}}{2 i}, \cos (x) = \frac{e^{i x} + e^{- i x}}{2}$ Die Additionstheoreme sind: $\begin{matrix} \sin (x + y) = \sin (x) \cos (y) + \cos (x) \sin (y) \\ \cos (x + y) = \cos (x) \cos (y) - \sin (x) \cos (y) \end{matrix}$