AoPSWiki
Trying to get to the USAMO in 2010? Our AIME Problem Series can help you get there! Click here to enroll today!

2001 IMO Shortlist Problems/G7

From AoPSWiki

Problem

Let O be an interior point of acute triangle ABC. Let A_1 lie on BC with OA_1 perpendicular to BC. Define B_1 on CA and C_1 on AB similarly. Prove that O is the circumcenter of ABC if and only if the perimeter of A_1B_1C_1 is not less than any one of the perimeters of AB_1C_1, BC_1A_1, and CA_1B_1.

Solution

This problem needs a solution. If you have a solution for it, please help us out by adding it.

Resources

Want to learn how to tackle those tough AMC/AIME/Olympiad counting and probability problems? Check out Art of Problem Solving's Intermediate Counting & Probability by David Patrick.
© Copyright 2008 AoPS Incorporated. All Rights Reserved. • FoundationPrivacyContact Us