Hi Christopher,

I'm sorry, I'm not sure I understand your first question, but I will offer some help for the second.

Let's think about how this triangle might look. We'll start with the two sides you know the lengths of:

So, you are trying to see what possible lengths the third side can have. Since You haven't been given any angles, we can create many different triangles by changing the angle that the above two lines meet at. Here are some examples:

Imagine that the vertex A is a pivot point. What happens as you rotate the side AC around the point A? From this can you see an upper and a lower bound for the length of the side BC?

Haley