sin 11Пи/12 * cos 11Пи/12= (sin(11Пи/12-11Пи/12)+sin(11Пи/12+11Пи/12))/2= (sin0+sin11П/6)/2=sin(2П-П/6)/2= -sin(П/6)/2=-(1/2)/2=-0.25
5sin 11Пи/12 * cos 11Пи/12=5*(-0.25)=-1.25
sin 11Пи/12 * cos 11Пи/12= (sin(11Пи/12-11Пи/12)+sin(11Пи/12+11Пи/12))/2= (sin0+sin11П/6)/2=sin(2П-П/6)/2= -sin(П/6)/2=-(1/2)/2=-0.25
5sin 11Пи/12 * cos 11Пи/12=5*(-0.25)=-1.25