Sin (-1350°), ctg (-4/3π), sin 19/6π

Sin(-1350)=-sin(1350)=-sin(3.360+270)=-sin(270)=-(-1)=1
cotg(-4pí/3)=-cotg(4pí/3)=-cptg(pí+pí/3)=-cotg(pí/3=-V3/3
sin(19pí/6)=sin(12pí/6+7pí/6)=sin(7pí/6)=-sinpí/6=-1/2