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

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

Applicare la formula: $x\cdot x^n$$=x^{\left(n+1\right)}$, dove $x^nx=\cos\left(x\right)^2\cos\left(x\right)$, $x=\cos\left(x\right)$, $x^n=\cos\left(x\right)^2$ e $n=2$

Applicare la formula: $a+b$$=a+b$, dove $a=2$, $b=1$ e $a+b=2+1$