Question

Решите неравенство:
а) 2cos x - √2 > 0

Answer 1

$2cos(x)- sqrt{2} textgreater 0 \ \ 2cos(x) textgreater sqrt{2} \ \ cos(x) textgreater frac{ sqrt{2} }{2}$

Первая точка $frac{ sqrt{2} }{2} = frac{pi}{4}$

Вторая точка $2pi- frac{pi}{4}= frac{7pi}{4}$

Ответ: $xin [ frac{pi}{4}+2pi n; frac{7pi}{4} +2pi n ] , nin Z$