8 cos^{2}x -10sinx-11=0

cos^{2}x = 1 - sin²x 8(1 - sin²x) - 10sin x - 11 = 0 8 - 8sin²x - 10sin x - 11 = 0 - 8sin²x - 10sin x - 3 = 0        D = 4    sin x₁ = -3/4                                                           sin x₂ = -1/2 x₁ = Arc sin(-3/4) = kπ+(-1)^k*arc sin(-3/4) = kπ+(-1)^k*( -0,84806 ) x₂ = Arc sin(-1/2) = kπ+(-1)^k*arc sin(-1/2) = kπ+(-1)^k*( -π/6 ).