Complex Number Trigonometry

You can represent the trigonometric functions as complex numbers

cos⁡θ=eiθ+e−iθ2\cos\theta = \frac{e^{i\theta} + e^{-i\theta}}{2} sin⁡θ=eiθ−e−iθ2i\sin\theta = \frac{e^{i\theta} - e^{-i\theta}}{2i} tan⁡θ=sin⁡θcos⁡θ=1i⋅eiθ−e−iθeiθ+e−iθ=−i⋅eiθ−e−iθeiθ+e−iθ\tan\theta = \frac{\sin\theta}{\cos\theta} = \frac{1}{i}\cdot\frac{e^{i\theta} - e^{-i\theta}}{e^{i\theta} + e^{-i\theta}} = -i\cdot\frac{e^{i\theta} - e^{-i\theta}}{e^{i\theta} + e^{-i\theta}}