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

Applicare la formula: $ab$$=ab$, dove $ab=- -\cos\left(x\right)$, $a=-1$ e $b=-1$

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