Applicare la formula: $\frac{a}{b}\frac{c}{f}$$=\frac{ac}{bf}$, dove $a=1$, $b=\sin\left(x\right)^2$, $c=1$, $a/b=\frac{1}{\sin\left(x\right)^2}$, $f=\cos\left(x\right)^2$, $c/f=\frac{1}{\cos\left(x\right)^2}$ e $a/bc/f=\frac{1}{\sin\left(x\right)^2}\frac{1}{\cos\left(x\right)^2}$