1969 IMO Problems/Problem 5

Revision as of 11:06, 20 October 2013 by Elvis (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

Given n > 4 points in the plane such that no three are collinear. Prove that there are at least (n-3)/2 convex quadrilaterals whose vertices are four of the given points.

Invalid username
Login to AoPS