Stosujemy wzory redukcyjne
[tex]cos150=cos(180-30)=-cos30\\tg120=tg(180-60)=-tg60\\sin120=sin(180-60)=sin60\\\\6cos150-5tg120+4sin120=6(-cos30)-5(-tg60)+4(sin60)=\\6*(-\frac{\sqrt3}2)-5*(-\sqrt3)+4*\frac{\sqrt3}2=-3\sqrt3+5\sqrt3+2\sqrt3=2\sqrt3+2\sqrt3=4\sqrt3[/tex]
