61st Kürschák Competition 1961

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1.  Given any four distinct points in the plane, show that the ratio of the largest to the smallest distance between two of them is at least √2.
2.  x, y, z are positive reals less than 1. Show that at least one of (1 - x)y, (1 - y)z and (1 - z)x does not exceed 1/4.
3.  Two circles centers O and O' are disjoint. PP' is an outer tangent (with P on the circle center O, and P' on the circle center O'). Similarly, QQ' is an inner tangent (with Q on the circle center O, and Q' on the circle center O'). Show that the lines PQ and P'Q' meet on the line OO'.

The original problems are in Hungarian. Many thanks to Péter Dombi for the translation.

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(C) John Scholes
jscholes@kalva.demon.co.uk
19 Apr 2003
Last corrected/updated 19 Apr 2003