Applicare la formula: $\frac{d}{dx}\left(ab\right)$$=\frac{d}{dx}\left(a\right)b+a\frac{d}{dx}\left(b\right)$, dove $d/dx=\frac{d}{dx}$, $ab=\cos\left(x\right)\cot\left(3x\right)$, $a=\cos\left(x\right)$, $b=\cot\left(3x\right)$ e $d/dx?ab=\frac{d}{dx}\left(\cos\left(x\right)\cot\left(3x\right)\right)$

Applicare l'identità trigonometrica: $\frac{d}{dx}\left(\cos\left(\theta \right)\right)$$=-\sin\left(\theta \right)$

Applicare l'identità trigonometrica: $\frac{d}{dx}\left(\cot\left(\theta \right)\right)$$=-\frac{d}{dx}\left(\theta \right)\csc\left(\theta \right)^2$, dove $x=3x$

Applicare la formula: $\frac{d}{dx}\left(x\right)$$=1$