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circumcircle of OIH passes through vertex A, prove an angle is 60^o

Source: Tuymaada Junior 2007 p4

May 12, 2019
geometrycircumcircleorthocenterincenterCircumcenterangles

Problem Statement

An acute-angle non-isosceles triangle ABC ABC is given. The point H H is its orthocenter, the points O O and I I are the centers of its circumscribed and inscribed circles, respectively. The circumcircle of the triangle OIH OIH passes through the vertex A A . Prove that one of the angles of the triangle is 60āˆ˜ 60^\circ .
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