Sin(6x)*sin(8x)=1/2 (cos(8x-6x)-cos(8x+6x))=1/2 (cos2x - cos14x)
cos4x*cos2x=1/2 (cos (6x) + cos (2x))
Тогда:
1/2 (cos2x - cos14x) = 1/2 (cos6x + cos2x)
cos2x - cos14x = cos6x + cos2x
- cos14x = cos6x
cos14x + cos6x = 0
2сos( (14x+6x)/2)*cos((14x-6x)/2)=0
2cos10x*cos4x=0
Тогда решение состоит из решений двух уравнений:
cos10x=0
cos4x=0
10x=Pi/2
x1=Pi/20
4x=Pi/2
x2=Pi/8