а) sinx ≥ –√2/2 б) cos4x ≤ √3/2
a) (–π/4)+2πn ≤ x ≤ (5π/4)+2πn, n ∈ Z см. рис. б) (π/6)+2πn ≤ 4x ≤ (11π/6)+2πn, n ∈ Z cм. рис. (π/24)+(π/2)n ≤ x ≤ (11π/24)+(π/2)n, n ∈ Z