спростити вираз:
1) cos(4x+3y)-cos4x·cos3y
2) sin(6x-12y)+sin12y·cos6y

cos(4x+3y)-cos4xcos3y=cos4xcos3y-sin4xsin3y-cos4xcos3y=-sin4xsin3y.
sin(6x-12y)+sin12ycos6x=sin6xcos12y-cos6xsin12y+sin12ycos6x=sin6xcos12y