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Harvard-MIT Mathematics Tournament #0im1

Harvard-MIT Mathematics TournamentHard

From module Cyclic Quadrilaterals

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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.
Quadrilaterals with perpendicular diagonalsCyclic quadrilateralsRadical axis theoremAngle chasing

Problem

Problem:

Convex quadrilateral ABCDABCD has right angles ∠A\angle A and ∠C\angle C and is such that AB=BCAB = BC and AD=CDAD = CD. The diagonals ACAC and BDBD intersect at point MM. Points PP and QQ lie on the circumcircle of triangle AMBAMB and segment CDCD, respectively, such that points PP, MM, and QQ are collinear. Suppose that m∠ABC=160∘m \angle ABC = 160^\circ and m∠QMC=40∘m \angle QMC = 40^\circ. Find MP⋅MQMP \cdot MQ, given that MC=6MC = 6.

figure

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