How can I simplify this expression:
f(theta)= sqrt(1+cos(4theta))
by eliminating the radical? Is there a specific idenity I have to use?
Thank you, I appreciate any help!
Maybe this can help
$\displaystyle \displaystyle \cos^2u = \frac{1+\cos(2u)}{2}$
$\displaystyle \displaystyle \cos u = \sqrt{\frac{1+\cos(2u)}{2}}$
$\displaystyle \displaystyle \sqrt{2}\cos u = \sqrt{1+\cos(2u)}$
Therefore
$\displaystyle \displaystyle \sqrt{2}\cos 2\theta = \sqrt{1+\cos(4\theta)}$
You still have $\displaystyle \displaystyle \sqrt{2}$ in the desired expression. Is this helpful at all?