Mathematics

Mathematics

Problem

Points A(0,0),  B(6,0),A(0,0),\; B(6,0), and C(2,4)C(2,4) are fixed in the coordinate plane. Point DD is chosen so that ∠ADB=∠ACB\angle ADB = \angle ACB. Prove that the points A,B,C,A, B, C, and DD lie on a common circle.

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