You start off with 4*(cos(x+(pi/3)))
Let's place the 4 aside for the time being:
Cos(u+j) = cos(u)*cos(j) - sin(u)*sin(j)
cos(x+(pi/3)) = cos(x)*cos(pi/3) - sin(x)*sin(pi/3)
cos(x+(pi/3)) = cos(x)/2 - (sqrt(3)/2)*sin(x)
Multiplying by the 4 we put aside:
4*cos(x+(pi/3)) = 2*cos(x) - 2*sqrt(3)*sin(x)
The correct answer is B
