Since the vector is making 30 degree with +ve direction of x axis. Therefore,it is making 60 degree with +ve direction of y axis If l=cos X where x is the angle made by vector with +ve direction of x axis which is 30 Then l= cos 30= root 3/2 And m=cos Y where y is the angle made by vector with +ve direction of y axis which is 60 Then m =cos 60=1/2 Therefore vector is root3/2i cap+1/2j cap