Question

Решите уравнение cos x=√2/2

Answer 1

$cos(x)= \frac{ \sqrt{2} }{2} \\...........................................\\cos(x)=m\\m=+-arccos(x)+2\pi k\\..........................................................\\x=+-arccos( \frac{\sqrt{2} }{2} )+2\pi k\\x=+- \frac{\pi}{4} +2\pi k$
k∈Z

Answer 2

$Cosx= \frac{ \sqrt{2} }{2}\\\\x=+-arcCos \frac{ \sqrt{2} }{2}+2 \pi n\\\\x=+- \frac{ \pi }{4}+2 \pi n$