Sin x - cos2x - 2 = 0

Question

Sin x - cos2x - 2 = 0

Answer 1

Cos 2x = 1 - 2 sin^2 x

sin x + 1 - 2 sin^2 x = 2
2 sin^2 x - sin x + 1 = 0
sin x = t [-1; 1]

2 t^2 - t + 1 = 0
D = 1 - 4*2*1 < 0
нет решений