tan(2x+$60^o$).cos(x+$75^o$)=0
⇔\(\left[ \begin{array}{l}tan(2x+60^o)=0\\cos(x+75^o)=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}2x+60^o=0\\x+75^o=90^o+180^ok,k∉Z\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=-30^o\\x=15^o+180^ok,k∉Z\end{array} \right.\)