Question

решить неравенство cosx<-1/2

Answer 1

Решение
cosx < - 1/2
arccos(-1/2) + 2πn < x < 2π - arccos(-1/2) + 2πn, n∈Z
2π/3 + 2πn < x < 2π - 2π/3 + 2πn, n∈Z
2π/3 + 2πn  < x < 4π/3 + 2πn, n∈Z