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HMMT 2014 #0jme

HMMT 2014Hard

From module Angle Chasing Mastery

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Understand the scale
Scale 0.5: Easiest math competition problems, often solvable even for early middle school students without experience. 1: Problems strictly for beginners, often at a moderate middle school level. 1.5: Problems for stronger beginner students, on the level of the middling problems in most middle school contests. 2: For motivated beginners, harder questions from the previous categories. 2.5: More advanced beginner problems, hardest questions from previous categories. 3: Early intermediate problems that require more creative thinking. 3.5: Tougher early intermediate problems that consistently stretch into higher-level creative thinking or conceptual knowledge. 4: Intermediate-level problems. 4.5: Upper intermediate problems approaching the upper bound for non-invitational sprint math competitions. 5: More difficult AIME problems or simple proof-based Olympiad-style problems. 6: High-level AIME-styled questions or introductory Olympiad-level questions. 7: Tougher Olympiad-level questions, may require more technical knowledge. 8: High-level Olympiad-level questions. 9: Expert Olympiad-level questions. 9.5: The hardest problems appearing on Olympiads which the strongest students could reasonably solve. 10: Historically notorious problems, generally unsuitable for even very hard competitions because they are exceedingly tedious, long, and difficult.
Brocard point, symmediansTangentsAngle chasingTriangle centers: centroid, incenter, circumcenter, orthocenter, Euler line, nine-point circle

Problem

Problem:

Let ABCABC be an acute triangle with circumcenter OO such that AB=4AB = 4, AC=5AC = 5, and BC=6BC = 6. Let DD be the foot of the altitude from AA to BCBC, and EE be the intersection of AOAO with BCBC. Suppose that XX is on BCBC between DD and EE such that there is a point YY on ADAD satisfying XY∥AOXY \parallel AO and YO⊥AXYO \perp AX. Determine the length of BXBX.

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