1. Zadatak

Budući da je

$$\begin{aligned} \operatorname{tg}192^\circ&=\operatorname{tg}(12^\circ+180^\circ)=\operatorname{tg}12^\circ,\\ \operatorname{tg}408^\circ&=\operatorname{tg}(48^\circ+360^\circ)=\operatorname{tg}48^\circ,\\ \operatorname{tg}168^\circ&=\operatorname{tg}(-12^\circ+180^\circ)=-\operatorname{tg}12^\circ, \end{aligned}$$

zadani izraz je jednak

$$\frac{\operatorname{tg}12^\circ+\operatorname{tg}48^\circ}{1-\operatorname{tg}12^\circ\cdot\operatorname{tg}48^\circ} =\operatorname{tg}(12^\circ+48^\circ) =\operatorname{tg}60^\circ=\sqrt3.$$