Applicare la formula: $\frac{\frac{a}{b}}{c}$$=\frac{a}{bc}$, dove $a=\cos\left(x\right)$, $b=\sin\left(x\right)$, $c=\sin\left(x\right)$, $a/b/c=\frac{\frac{\cos\left(x\right)}{\sin\left(x\right)}}{\sin\left(x\right)}$ e $a/b=\frac{\cos\left(x\right)}{\sin\left(x\right)}$