Odpowiedź:
a)
sin(- 2x) = - 1/2
sin(- 2x) = - sin30°
- sin2x = - sin30°
2x = 30°
x- 30° : 2 = 15°
b)
4cos(3x - 2π/3) = 2√3
cos(3x - 2π/3) = 2√3/4 = √3/2
cos(3x - 2π/3) = cos30°
3x - 2π/3 = 30°
3x - 2 * 180°/3 = 30°
3x - 2 * 60° = 30°
3x - 120° = 30°
3x = 30° + 120° = 150°
x = 150° : 3 = 50°
cos5x ≥ 1/2
cos5x ≥ cos60°
5x ≥ 60°
x ≥ 60° : 5
x ≥ 12°
