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can segments of tangents of sphere circumscribed on 4dron, form triangle?

Source: Sharygin Geometry Olympiad 2016 First Round P23 grades 10-11

July 25, 2018
geometry3D geometrysphere

Problem Statement

A sphere touches all edges of a tetrahedron. Let a,b,ca, b, c and d be the segments of the tangents to the sphere from the vertices of the tetrahedron. Is it true that that some of these segments necessarily form a triangle?
(It is not obligatory to use all segments. The side of the triangle can be formed by two segments)