Difference between revisions of "2005 IMO Problems/Problem 1"

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==Problem==
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Six points are chosen on the sides of an equilateral triangle <math>ABC</math>: <math>A_1, A_2</math> on <math>BC</math>, <math>B_1</math>, <math>B_2</math> on <math>CA</math> and <math>C_1</math>, <math>C_2</math> on <math>AB</math>, such that they are the vertices of a convex hexagon <math>A_1A_2B_1B_2C_1C_2</math> with equal side lengths. Prove that the lines <math>A_1B_2, B_1C_2</math> and <math>C_1A_2</math> are concurrent.
 
Six points are chosen on the sides of an equilateral triangle <math>ABC</math>: <math>A_1, A_2</math> on <math>BC</math>, <math>B_1</math>, <math>B_2</math> on <math>CA</math> and <math>C_1</math>, <math>C_2</math> on <math>AB</math>, such that they are the vertices of a convex hexagon <math>A_1A_2B_1B_2C_1C_2</math> with equal side lengths. Prove that the lines <math>A_1B_2, B_1C_2</math> and <math>C_1A_2</math> are concurrent.
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==Solution==
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{{solution}}
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==See Also==
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{{IMO box|year=2005|before=First Problem|num-a=2}}

Latest revision as of 00:56, 19 November 2023

Problem

Six points are chosen on the sides of an equilateral triangle $ABC$: $A_1, A_2$ on $BC$, $B_1$, $B_2$ on $CA$ and $C_1$, $C_2$ on $AB$, such that they are the vertices of a convex hexagon $A_1A_2B_1B_2C_1C_2$ with equal side lengths. Prove that the lines $A_1B_2, B_1C_2$ and $C_1A_2$ are concurrent.

Solution

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See Also

2005 IMO (Problems) • Resources
Preceded by
First Problem
1 2 3 4 5 6 Followed by
Problem 2
All IMO Problems and Solutions