Applicare la formula: $x+a=b$$\to x=b-a$, dove $a=x$, $b=0$, $x+a=b=x+\tan\left(xy\right)=0$, $x=\tan\left(xy\right)$ e $x+a=x+\tan\left(xy\right)$

Applicare la formula: $a=b$$\to inverse\left(a,a\right)=inverse\left(a,b\right)$, dove $a=\tan\left(xy\right)$ e $b=-x$

Applicare la formula: $\arctan\left(\tan\left(\theta \right)\right)$$=\theta $, dove $x=xy$

Applicare la formula: $ax=b$$\to x=\frac{b}{a}$, dove $a=x$, $b=\arctan\left(-x\right)$ e $x=y$