Sin 4x + 2sin² 7x = 1
Sin4x+2sin²7x-1=0 sin4x-cos14x=0 sin4x-sin(π/2-14x)=0 2sin(9x-π/4)cos(π/4-5x)=0 sin(9x-π/4)=0 9x-π/4=πn 9x=π/4+πn x=π/36+πn/9,n∈z cos(5x-π/4)=0 (косинус четная функция) 5x-π/4=π/2+πk 5x=3π/4+πk x=3π/20+πk/5,k∈z