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PrintTeam Selection Test for JBMO 2024
Turkey 2024 geometry
Problem
Let be an acute triangle, be the midpoint of the side and be the foot of the altitude from . Let be a point on the segment such that . Let the second intersection point of the circumcircle of and line be . Let the second intersection point of the circumcircle of and line be . Prove that .

Solution
Since , , , are concyclic we have and hence is a right triangle. Since lies on the circle centered at and , we can see that is tangent to the circumcircle of . Using the power of the point with respect to the circles and we get and from the Euclid relations in the triangle we are done.
Techniques
Cyclic quadrilateralsTangentsRadical axis theoremAngle chasing