MathDB
points of tangency of incircles to 4 edges in tetrahedron are concyclic

Source: Polish second round 1995 p5

January 19, 2020
geometry3D geometrytetrahedronConcyclicincircle

Problem Statement

The incircles of the faces ABCABC and ABDABD of a tetrahedron ABCDABCD are tangent to the edge ABAB in the same point. Prove that the points of tangency of these incircles to the edges AC,BC,AD,BDAC,BC,AD,BD are concyclic.
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