Question

1) Sin2π/5+ sin π/5
2) cos11π/12+cos 3π/4
3) cos (π/3-a) +cos a
4) sin (π/6+a)-sin (π/6-a)
5) sin π/6-sin π/9
6) sin a-sin (a+π/3)
Преобразовать в произведения. ​