1) Find the solutions of in the interval

I can determine that there are 4 solutions that need to be found, but I can only find 2 of them (). How do I find the others?

2) Find the period of the graph

I know how to find the period of functions containing either sin or cos, but not both. Can someone give me a crash course on how to do this?

Thanks in advance.

(Apologies for the choppy equation structure.)