Question

Решите уравнение 2cosx=√8/2

Answer 1

$2cosx= \frac{ \sqrt{8} }{2}$

$2cosx= \frac{2 \sqrt{2} }{2}$

$2cosx= \sqrt{2}$

$cosx= \frac{ \sqrt{2} }{2}$

x = ± $arccos \frac{ \sqrt{2} }{2} +2 \pi n$, n∈Z

x = ± $\frac{ \pi }{4}+2 \pi n,$ n∈Z