MathDB

34

Part of 1970 IMO Longlists

Problems(1)

None of the circles contains the pentagon - ILL 1970, P34

Source:

5/21/2011
In connection with a convex pentagon ABCDEABCDE we consider the set of ten circles, each of which contains three of the vertices of the pentagon on its circumference. Is it possible that none of these circles contains the pentagon? Prove your answer.