cos 3alfa + 5 sin 2alfaalfa=60 градусов
cos 3 *60 + 5*cos 2*60 = cos 180 + 5* cos 120 = 0 - 5*1/2 = -2.5
cos 3alfa + 5 sin 2alfa
alfa=60 градусов
cos 3 *60 + 5*cos 2*60 = cos 180 + 5* cos 120 = 0 - 5*1/2 = -2.5