Difference between revisions of "1996 USAMO Problems/Problem 3"

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Let <math>ABC</math> be a triangle. Prove that there is a line <math>l</math> (in the plane of triangle <math>ABC</math>) such that the intersection of the interior of triangle <math>ABC</math> and the interior of its reflection <math>A'B'C'</math> in <math>l</math> has area more than <math>\frac{2}{3}</math> the area of triangle <math>ABC</math>.
 
Let <math>ABC</math> be a triangle. Prove that there is a line <math>l</math> (in the plane of triangle <math>ABC</math>) such that the intersection of the interior of triangle <math>ABC</math> and the interior of its reflection <math>A'B'C'</math> in <math>l</math> has area more than <math>\frac{2}{3}</math> the area of triangle <math>ABC</math>.
  
==Hint==
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==Solution==
Without loss of generality, set A(0,0), B(a,1), and C(b,1). The line of reflection should be y = k for some constant k.
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{{solution}}
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== See Also ==
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{{USAMO box|year=1996|num-b=2|num-a=4}}
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{{MAA Notice}}
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[[Category:Olympiad Geometry Problems]]

Revision as of 09:25, 20 July 2016

Problem

Let $ABC$ be a triangle. Prove that there is a line $l$ (in the plane of triangle $ABC$) such that the intersection of the interior of triangle $ABC$ and the interior of its reflection $A'B'C'$ in $l$ has area more than $\frac{2}{3}$ the area of triangle $ABC$.

Solution

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See Also

1996 USAMO (ProblemsResources)
Preceded by
Problem 2
Followed by
Problem 4
1 2 3 4 5
All USAMO Problems and Solutions

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