Question

Решить равенство
2 cos x < 1

Answer 1

2 cos x < 1
 cos x < 1/2
arccos(1/2) + 2πn < x < 2π - arccos(1/2) + 2πn, n∈Z
π/3 + 2πn < x < 2π - π/3 + 2πn, n∈Z
π/3 + 2πn < x < 5π/3 + 2πn, n∈Z