Решите пожалуйста! 18.6, 18.7, 18.8 под буквой в!

1) sinx = t, -1 ≤ t ≤ 1 4t² + 11t - 3 = 0 D = 121 + 48 = 169 t₁ = (-11-13)/8 = -3 < - 1 - не удовлетворяет ОДЗ t₂ = (-11 + 13)/4 = 0.5 sinx = 0.5 x = (-1)ⁿ * π/3 + πn, n∈Z 2) cosx = t, -1 ≤ t ≤ 1 2t² - t - 3 = 0 D = 1 + 24 = 25 t₁ = (1+5)/4 = 6/4 > 1 - не удовлетворяет ОДЗ t₂ = (1 - 5)/4 = -1 cosx = -1 x = π + 2πn, n∈Z 3) cos²x = 1 - sin²x 5 - 5sin²x + 6sinx - 6 = 0 5sin²x - 6sinx + 1 = 0 sinx = t, -1 ≤ t ≤ 1 5t² - 6t + 1 = 0 D = 36 - 20 = 16 t₁ = (6+4)/10 = 1 t₂ = (6-4)/10 = 0.2 sinx = 1 x₁ = π/2 + 2πn, n∈Z sinx = 0.2 x₂ = (-1)ⁿarcsin(0.2) + πn, n∈Z 0 ≤ arcsin(0.2) ≤ π/2