I do know i should start a new thread for every question but I would end up with 4 threads in several forums each containing a (probably) silly question, so I think it is ok to post here.
1. To show given the lengths of a triangle this triangle exists, what do I have to do?
I thought of the inequality (a+b<c) and the sides being positve, what else?
2. Given a cubic function, do the ends always point in different directions(+ and -)?
3.Given 0<a<b is it sufficient to say sqrt(a)<sqrt(b) just by something like it is monotone?
4. A graph without circles is a tree. Does this apply to directed graphs, too?
Thanks in advance!