1) 3 cos 4x cos 2x-3 sin 4x sin 2x=-3
2. tg(π/3-a), если sin a=1/3, π/3

3(Cos4xCos2x -Sin4xSin2x) = -3Cos4xCos2x -Sin4xSin2x = -1Cos6x = -16x = π + 2πk , k ∈Zx = -π/6 +πk/3, k ∈Z