cos3x/(sin3x-2sinx)=tgx

cos(3x)/(sin(3x) - 2sin(x)) = tg(x)(4cos³(x) - 3cos(x))/(3sin(x) - 4sin³(x) - 2sin(x)) = tg(x)(cos(x)*(4cos²(x) - 3)/(sin(x)*(1 - 4sin²(x))) = tg(x)cos(x)*(2cos(2x) - 1)/(sin(x)*(2cos(2x) - 1) = tg(x)ctg(x) = tg(x) --> tg(x) = ±1 --> x = π/4 + πk/2, k - целое.