Question

РЕШИТЬ УРАВНЕНИЕ ПЛИЗ ХЕЛП АЛГЕБРА

Answer 1

$cos\frac{x}{3}\cdot cos\frac{\pi}{6}+sin\frac{\pi}{3}\cdot sin\frac{\pi}{6}=-1\\\\cos(\frac{x}{3}-\frac{\pi}{6})=-1\\\\\frac{x}{3}-\frac{\pi}{6}=\pi +2\pi n\; ,\; n\in Z\\\\\frac{x}{3}=\pi +\frac{\pi}{6}+2\pi n\; ,\; n\in Z\\\\\frac{x}{3}=\frac{7\pi }{6}+2\pi n\; ,\; n\in Z\\\\x=\frac{7\pi }{2}+6\pi n\; ,\; n\in Z$