Question

Solve cos2x=1/√(2)
Please show steps!

Answer 1

what are inteval for x?

Answer 2

\[0\le x \le2\pi\]

Answer 3

Well, you know that\[\cos\left(\pi/4\right)=\frac{\sqrt2}{2}=\frac{1}{\sqrt2}.\]Immediately you know that\[x=\frac{\pi}{8}+\pi k,\]where \(k\in\mathbb{Z}\) are the solutions.

Answer 4

that really helped, thanks!

Answer 5

i think the answer not complete...
how about u across, if x=7pi/8 ?
right to, isn't it?