sin(30+a) - cos (60+a) sin(30+a) + cos (60+a) =

1.sin(30°-a)-sin(60°-a)=sin(30°)cos(a)-cos(30°)sin(a)-(sin(60°)cos(a)-cos(60°)sin(a))=1/2*cos(a)-sqrt(3)/2*sina-sqrt(3)/2*sin(a)+1/2*cos(a)=

=cos(a)+√3cos(a)

2.sin(30-a)-cos(60-a)=sin30*cos(a)-sin(a)*cos30-cos60*cos(a)-sin60*sin(a)=cos(a)/2-√3*sin30/2-cos(a)/2-√3*sin(a)/2=√3*sin30/2-√3sin(a)/2.

3. cos(a)+√3cos(a) / √3*sin30/2-√3sin(a)/2