Difference between revisions of "1993 OIM Problems/Problem 5"

(Created page with "== Problem == Let <math>P</math> and <math>Q</math> be two different points on the plane. Let us denote by <math>m(PQ)</math> the bisector of the segment <math>PQ</math>. Let...")
 
 
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a. If <math>P</math> and <math>Q</math> are points distinct from <math>S</math>, then <math>m(PQ)</math> intersects <math>S</math>.
 
a. If <math>P</math> and <math>Q</math> are points distinct from <math>S</math>, then <math>m(PQ)</math> intersects <math>S</math>.
  
b. If <math>P_1Q_1</math>, <math>P_2Q_2</math>and <math>P_3Q_3</math>are three different segments whose ends are points of <math>S</math>, then no point of <math>S</math> belongs simultaneously to the three lines <math>m(P_1Q_1)</math>, <math>m(P_2Q_2)</math>. and <math>m(P_3Q_3)</math>.
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b. If <math>P_1Q_1</math>, <math>P_2Q_2</math>, and <math>P_3Q_3</math>are three different segments whose ends are points of <math>S</math>, then no point of <math>S</math> belongs simultaneously to the three lines <math>m(P_1Q_1)</math>, <math>m(P_2Q_2)</math>, and <math>m(P_3Q_3)</math>.
  
 
Determine the number of points that <math>S</math> can have.
 
Determine the number of points that <math>S</math> can have.

Latest revision as of 14:19, 13 December 2023

Problem

Let $P$ and $Q$ be two different points on the plane. Let us denote by $m(PQ)$ the bisector of the segment $PQ$. Let $S$ be a finite subset of the plane, with more than one element satisfying the following properties:

a. If $P$ and $Q$ are points distinct from $S$, then $m(PQ)$ intersects $S$.

b. If $P_1Q_1$, $P_2Q_2$, and $P_3Q_3$are three different segments whose ends are points of $S$, then no point of $S$ belongs simultaneously to the three lines $m(P_1Q_1)$, $m(P_2Q_2)$, and $m(P_3Q_3)$.

Determine the number of points that $S$ can have.

~translated into English by Tomas Diaz. ~orders@tomasdiaz.com

Solution

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See also

https://www.oma.org.ar/enunciados/ibe8.htm