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point lies on common chord (Slovenia National MO 2001 3rd Grade P3)

Source:

April 7, 2021
geometry

Problem Statement

A point DD is taken on the side BCBC of an acute-angled triangle ABCABC such that AB=ADAB = AD. Point EE on the altitude from CC of the triangle is such that the circle k1k_1 with center EE is tangent to the line ADAD at DD. Let k2k_2 be the circle through CC that is tangent to ABAB at BB. Prove that AA lies on the line determined by the common chord of k1k_1 and k2k_2.