Applicare la formula: $\tan\left(\arccos\left(\theta \right)\right)$$=\frac{\sqrt{1-\theta ^2}}{\theta }$, dove $x=\frac{x}{2}$

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

Applicare la formula: $\left(\frac{a}{b}\right)^n$$=\frac{a^n}{b^n}$, dove $a=x$, $b=2$ e $n=2$

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

Applicare la formula: $-\frac{b}{c}$$=\frac{expand\left(-b\right)}{c}$, dove $b=x^2$ e $c=4$