cosx = 0 или sinx + cosx = 0
x₁ = π/2 + πn, n∈Z sinx = -cosx | : cosx
tgx = -1
x = arctg(-1) + πn
x = -arctg(1) + πn
x₂ = -π/4 + πn, n∈Z
ответ: x₁ = π/2 + πn, n∈Z; x₂ = -π/4 + πn, n∈Z
