sin(x)+sin(y) = 2·sin(½(x+y))·cos(½(x-y))
sin 200° + sin 20°=2·sin(½(220°))·cos(½(180°)) =2·sin110°cos90° =
= 2·sin110°*0=0
sin(x)+sin(y) = 2·sin(½(x+y))·cos(½(x-y))
sin 200° + sin 20°=2·sin(½(220°))·cos(½(180°)) =2·sin110°cos90° =
= 2·sin110°*0=0