Решите неравенство: sin x × cos pi÷10 - cos x - вопрос №1010229634239 от SonyaCarrol 01.11.2020 17:35

Question

Алгебра: Решите неравенство: sin x × cos pi÷10 - cos x × sin pi÷10 ≥ √2÷2;

SonyaCarrol · Answer

Sin x•cos π/10 - cos x•sin π/10 = sqrt2/2sin (x - π/10) = sqrt2/2π/4 + 2πn = x - π/10 = 3π/4 + 2πn, n є Zπ/4 + π/10 + 2πn = x = 3π/4 + π/10 + 2πn, n є Z7π/20 + 2πn = x = 17π/20 + 2πn, n є Zx є [7π/20 + 2πn; 17π/20 + 2πn], n є Z...