Applying the trigonometric identity: $\cot\left(\theta \right) = \frac{\cos\left(\theta \right)}{\sin\left(\theta \right)}$

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

Applicare l'identità trigonometrica: $\frac{\sin\left(\theta \right)}{\cos\left(\theta \right)}$$=\tan\left(\theta \right)$, dove $x=a$