Aplicamos a regra: $\frac{\frac{a}{b}}{c}$$=\frac{a}{bc}$, onde $a=\cos\left(x\right)^2$, $b=\sin\left(x\right)^2$, $c=1-\sin\left(x\right)$, $a/b/c=\frac{\frac{\cos\left(x\right)^2}{\sin\left(x\right)^2}}{1-\sin\left(x\right)}$ e $a/b=\frac{\cos\left(x\right)^2}{\sin\left(x\right)^2}$