Question

Решите уравнение:
cos(pi/4+2x)=1/2
Подробно, пожалуйста

Answer 1

$cost=a\; \; \Rightarrow \; \; t=\pm arccosa+2\pi n,\; n\in Z\\\\\\cos(\frac{\pi }{4}+2x)=\frac{1}{2}\; \; \; \; \; \; \Big [\, t=\frac{\pi }{4}+2x\, \Big ]\\\\\frac{\pi }{4}+2x=\pm arccos\frac{1}{2}+2\pi n,\; n\in Z\\\\\frac{\pi }{4}+2x=\pm \frac{\pi }{3}+2\pi n,\; n\in Z\\\\2x=\pm \frac{\pi }{3}-\frac{\pi }{4}+2\pi n,\; n\in Z\\\\x=\pm \frac{\pi }{6}-\frac{\pi }{4}+\pi n= \left [ {{-\frac{\pi}{12}+\pi n,\; n\in Z} \atop {-\frac{5\pi }{12}+\pi n,\; n\in Z}} \right.$