b) $N=\cos(180^0-x)-2\sin(180^0-x)+\cos x+2\sin(90^0-x)=$$-\cos x -2\sin x+\cos x+2\cos x=2\cos x- 2\sin x$
b) N=cos(1800−x)−2sin(1800−x)+cosx+2sin(900−x)=−cosx−2sinx+cosx+2cosx=2cosx−2sinx
b) $N=\cos(180^0-x)-2\sin(180^0-x)+\cos x+2\sin(90^0-x)=
$$-\cos x -2\sin x+\cos x+2\cos x=2\cos x- 2\sin x$