Help explaining how to find the period of a function...

[frauleinedoctor]

I dont quite understand the way my book explains it...

the problem I have down is

(x) = 3 cot 4x ,

but Im sure Ill be able to do it once I am familiarized with what to do. I have a unit circle.

 

[frauleinedoctor]

whoops:

the problem is actly f(x) = ....


orgot the f.