Confusing concepts

Hi all,
I want to make sure that I understood some concepts of graph theory.
I had a Theorem which generally states "The routing protocol guarantees packet delivery". See Theorem 1
in http://ieeexplore.ieee.org/stamp/stamp.jsptp=&arnumber=4654241&isnumber=4654185

Note: If you can not get it let me know.

So when I proved it, somebody told me that how did you prove it, so my answer was by contradiction, which gave me the impression that this is a bad answer.

After some readings, can I say that I proved it based on Geometric Graph Theory
where I am using for my Theorem "a Euclidean graph which is a graph in which the vertices represent points in the plane, and the edges are assigned lengths equal to the Euclidean distance between those points. " From http://en.wikipedia.org/wiki/Geometric_graph_theory

And then I will use the proof by contradiction to prove my protocol.
Is it what I should have said when I have been asked?

Thanks in advance
tarektarek

Well, it should be sufficient no matter how you PROVE it. Of course, if you don't actually prove it, it doesn't much matter what your approach was, either.

Generally, the question "How did you prove it" is not a question of what sort of proof you may have designed, rather exactly what the proof is. Show your questioner the proof!

Thank you very much TKHunny for the valuable answer.