Question 962473
If x is the angle and
{{{cos(x)=sqrt(2)/2}}}
then we have that
{{{adjacent/hypotenuse=sqrt(2)/2}}}
and so, if we recall our special triangle with legs length √2, and hypotenuse 2 (this is the same as the triangle with legs length 1 and hypotenuse length √2), we get that the angle is
{{{x=pi/4}}}
which is 45°.