MathDB
ARO 2011 11-8

Source:

May 3, 2011
geometrycircumcircletrigonometry

Problem Statement

Let NN be the midpoint of arc ABCABC of the circumcircle of triangle ABCABC, let MM be the midpoint of ACAC and let I1,I2I_1, I_2 be the incentres of triangles ABMABM and CBMCBM. Prove that points I1,I2,B,NI_1, I_2, B, N lie on a circle.
M. Kungojin
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