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Bosnia and Herzegovina TST 2012 Problem 1

Source:

May 19, 2012
geometrycircumcirclegeometry proposed

Problem Statement

Let DD be the midpoint of the arc BACB-A-C of the circumcircle of ABC(AB<AC)\triangle ABC (AB<AC). Let EE be the foot of perpendicular from DD to ACAC. Prove that CE=BA+AC2|CE|=\frac{|BA|+|AC|}{2}.