Given a set of 9 points, no 3 collinear
, prove there must be a subset of 5 that forms a convex pentagon.
(In reply to Happy Ending
by Brian Smith)
Several of my recent problems lately have come directly or indirectly from a really interesting book I'm reading. I plan to share the book in the forums when I finish the book.
As for this problem...
well I thought I could solve it with careful deduction through methods similar to 5 points to convex quad. Even though I hadn't actually finished it when I submitted this I thought it would be D4ish. Unfortunately the number of cases to consider becomes huge. It got too complicated to tease them all out. This is definitely a d5 or higher problem. Even if I do manage it it will be way too much to type out as an official solution.
Oh well I guess these things happen. I apologize for any wasted time.
Posted by Jer
on 2009-10-18 01:22:37