help in a question : covering points with 2 circles

[nuzzle]

I think ur answer is ok

Well, I can prove it's correct.

You only have to show that the optimal pair of circles is to be found among the set of minimal circles (*) (and not just any circles). And that's easy. Say you have any circle that's not minimal and is covering some points. Then you can always shrink it to become a minimal circle still covering the same points. And since this circle was shrunk it's a better choise than the original circle. It follows that only minimal circles need be considered. So if you exhaustively consider every possible pair of minimal circles you're guaranteed to find the optimal pair(s).

(*) A minimal circle is a 3, 2 or 1 point circle as defined in my previous reply.