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6 points concyclic, extending sides of a triangle at both ends

Source: Norwegian Mathematical Olympiad 2009 - Abel Competition p3a

September 5, 2019
geometryConcyclic

Problem Statement

In the triangle ABCABC the edge BCBC has length aa, the edge ACAC length bb, and the edge ABAB length cc. Extend all the edges at both ends – by the length aa from the vertex A,bA, b from BB, and cc from CC. Show that the six endpoints of the extended edges all lie on a common circle. https://cdn.artofproblemsolving.com/attachments/8/7/14c8c6a4090d4fade28893729a510d263e7abb.png