$$\left. \begin{array} { l } { \sin \theta - \cos \theta = 2 n \pi - \frac { \pi } { 2 } } \\ { ? } \end{array} \right.$$
$\theta =-i\ln(\left(\frac{1}{4}-\frac{1}{4}i\right)\sqrt{-8\pi ^{2}n+16\left(\pi n\right)^{2}+\pi ^{2}-8}+\pi \left(-1+i\right)n+\pi \left(\frac{1}{4}-\frac{1}{4}i\right))+2\pi n_{1}\text{, }n_{1}\in \mathrm{Z}\text{, }n\in \mathrm{C}$
$\theta =-i\ln(\left(-\frac{1}{4}+\frac{1}{4}i\right)\sqrt{-8\pi ^{2}n+16\left(\pi n\right)^{2}+\pi ^{2}-8}+\pi \left(-1+i\right)n+\pi \left(\frac{1}{4}-\frac{1}{4}i\right))+2\pi n_{2}\text{, }n_{2}\in \mathrm{Z}\text{, }n\in \mathrm{C}$
