68

Part of 1969 IMO Shortlist

Problems(1)

Prove we can form convex quad given 5 points

Source:

(USS 5)

5

points in the plane, no three of which are collinear, prove that we can choose

4

points among them that form a convex quadrilateral.

geometrypoint setconvex quadrilateralcombinatorial geometryIMO ShortlistIMO Longlist