Solve 0=tan^-1y/x-z

$$0 = \tan ^ { - 1 } y / x - z$$

Solve for x

$$\left\{\begin{matrix}x=y\cot(z)\text{, }&\exists n_{2}\in \mathrm{Z}\text{ : }\left(z>\frac{\pi n_{2}}{2}\text{ and }z<\frac{\pi n_{2}}{2}+\frac{\pi }{2}\right)\text{, }not(n_{2}<-1)\text{ and }not(n_{2}>0)\text{ and }y\neq 0\\x\neq 0\text{, }&\exists n_{1}\in \mathrm{Z}\text{ : }z=\pi n_{1}\text{, }n_{1}=0\text{ and }y=0\end{matrix}\right.$$

Solve for y

$$y=x\tan(z)$$

$$x\neq 0\text{ and }\nexists n_{1}\in \mathrm{Z}\text{ : }z=\pi n_{1}+\frac{\pi }{2}\text{ and }|z|\leq \frac{\pi }{2}$$