2cosx-sinx-1=0 срочно!!!!

2cosx - sinx - 1 = 0 2cos³(x/2) - 2sin²9x/) - 2sin(x/2)cos(x/2) - sin³(x/) - cos²(x/2) = 0 cos²(x/) - 2sin(x/2)cos(x/2) - 3sin²(x/2) = 0 делим на ( cos³x/2 ≠ 0) 3tg³(x/2) + 2tg(x/2) - 1 = 0 D = 4 + 4*3*1 = 16 1)  tg(x/2) = (- 2 - 4)/6 tg(x/2) = - 1 x/2 = - π/4 + πk, k∈Z x₁ = - π/2 + 2πk, k∈Z 2)  tg(x/2) = ( - 2 + 4)/6 tg(x/2) = 1/3 x/2 = arctg(1/3) + πn, n∈Z x₂ = 2*arctg(1/3) + 2πn, n∈Z