Applicare la formula: $a+\frac{b}{c}$$=\frac{b+ac}{c}$, dove $a=simpli\left(\frac{\cos\left(x\right)}{\tan\left(x\right)}\right)$, $b=-1$, $c=\sin\left(x\right)$, $a+b/c=simpli\left(\frac{\cos\left(x\right)}{\tan\left(x\right)}\right)+\frac{-1}{\sin\left(x\right)}$ e $b/c=\frac{-1}{\sin\left(x\right)}$