1-2 sin'2 3x >= -1/2

Question

1-2 sin'2 3x >= -1/2

Answer 1

2sin^2 3x≤ 3/2

sin^2 3x ≤ 3/4

sin3x ≤ √3 /2

2Пk - П - П/3 ≤ 3х ≤ П/3 + 2Пk

- 4/9 П+2/3 Пk ≤ x ≤ П/9 + 2/3 Пk