Y= (cosx)/(sin^2 x) * tg x(π/2-x)

cosx*((sinx/cosx) - cosx) = -sin^2(x) sinx - cos^2(x) + sin^2(x) = 0 sinx - 1 + sin^2(x) + sin^2(x)) = 0 2sin^2(x) + sinx - 1 = 0 замена: sinx = t ∈[-1;1] 2t^2 + t - 1 = 0, D = 1 + 8 = 9 t1 = (-1-3)/4 = -4/4 = -1 t2 = (-1+3)/4 = 2/4 = 1/2 1) sinx = -1, x = -π/2 + 2πk, k∈Z 2) sinx = 1/2 x = π/6 + 2πk, k∈Z x = 5π/6 + 2πk, k∈Z