Question

simplify given that all angles are between 0 and pi
Cos(2arccos sqrt2/2)

Answer 1

\[\cos^{-1} \frac{\sqrt{2}}{2}=\frac{\pi}{4}, \frac{7\pi}{4}\]

Answer 2

When you multiply those angles by 2 you get:
\[\frac{\pi}{2},\frac{7\pi}{2}\]

Answer 3

\[\cos \frac{\pi}{2}=0; \cos \frac{7\pi}{2}=0\]