Question

Решить уравнение
Cos x=0,7
2cos2x=корень из 2
ПОМОГИТЕ

Answer 1

$cos x=0.7\x=pmarccos0.7+2pi n,n in mathbb{Z}\ \ 2cos2x=sqrt{2}\cos2x=dfrac{1}{sqrt{2}}\ 2x=pmdfrac{pi}{3}+2pi n,n in mathbb{Z}\ x=pmdfrac{pi}{6}+pi n,n in mathbb{Z}$