3sinx=sin(2y+x)3sin(x+y-y)=sin(y+x+y)3[sin(x+y)cosy-cos(x+y)siny]=sin(x+y)cosy+cos(x+y)sinysin(x+y)cosy=2cos(x+y)sinysin(x+y)/cos(x+y)=2siny/cosytan(x+y)=2tany