You CANNOT have no clue. You simply must have SOME tools at your disposal.
It is a math problem. You cannot break it. Try ANYTHING. Don't just stare at it.
Trust me on this.
Why not multiply numerator and denominator by \(\displaystyle \sqrt{1+cos(x)}\), just to see what happens?
It's not an easy problem, any way you look at it, but it is not impossible unless you give up. Hang in there, Review the discussion before the problem section. There must be some sort of clue in there.