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