MathDB
2017 G9: Concurrency in Cyclic Quadrilateral

Source:

January 29, 2017
2017geometrycyclic quadrilateral

Problem Statement

Let ABC\triangle ABC be an acute triangle with circumcenter OO, and let QAQ\neq A denote the point on (ABC)\odot (ABC) for which AQBCAQ\perp BC. The circumcircle of BOC\triangle BOC intersects lines ACAC and ABAB for the second time at DD and EE respectively. Suppose that AQAQ, BCBC, and DEDE are concurrent. If OD=3OD=3 and OE=7OE=7, compute AQAQ.