Question

$2 sqrt{2} cos^{2} x=1+ sqrt{2}$ Найти x

Answer 1

$cos^2x= frac{1+ sqrt{2} }{2 sqrt{2} }$
$cos x= sqrt{ frac{1+ sqrt{2} }{2 sqrt{2} } }$=z
x = Arc cos z = $2k pi +- frac{ pi }{8}$