Question

Solve the equation for [0,2pi] cos2x=1/sqrt2

Answer 1

$cos(2x) = \frac{1}{\sqrt{2}}$
$cos(2x) = \frac{1}{\sqrt{2}} * \frac{\sqrt{2}}{\sqrt{2}}$
$cos(2x) = \frac{\sqrt{2}}{2}$
$cos(2x) = cos(45)$
$cos(x) = cos(22.5)$
$x = 22.5$