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