Question

3. Решите уравнение 4 cos^2 3х – 3 = 0.​

Answer 1

$4cos^2 3x - 3 = 0\cos^2 3x = frac{3}{4}\cos 3x = pm frac{sqrt3}{2}\3x = pm frac{pi}{6} + pi k\x = pm frac{pi}{18} + frac{pi}{3}k, k in mathbb {Z}$