IMO Shortlist 1973 problem 5
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arhiva2. travnja 2012. A circle of radius 1 is located in a right-angled trihedron and touches all its faces. Find the locus of centers of such circles.
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A circle of radius 1 is located in a right-angled trihedron and touches all its faces. Find the locus of centers of such circles.
Izvor: Međunarodna matematička olimpijada, shortlist 1973