sin2x - sinx = 0 sin2x - cosx =0
sin(2x)-sin(x)=0sin(2x)-cos(x)=0
sin(2x)-sin(x)=-cos(x)=0
sin(2x)+cos(x)=sin(x)/\cos(x)=0
2sin(x)cos(x)-sin(x)=-cox(x)=0
2sin (x/2)cos(x/2)(2cos(x)-1)=-cos(x)=0