What is the period of fx = cos(cos x) + cos(sin x)
The cos and sin functions both have period , so it will certainly be true that Thus f(x) repeats itself after an interval of The only thing that you have to be wary about is whether that is the shortest interval after which f(x) repeats itself, or whether it might have a shorter period. Not wanting to give away the whole answer, I'll leave you to think about that.