IMO Shortlist 1969 problem 12
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arhiva2. travnja 2012. 
Given a unit cube, find the locus of the centroids of all tetrahedra whose vertices lie on the sides of the cube.
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$(CZS 1)$ Given a unit cube, find the locus of the centroids of all tetrahedra whose vertices lie on the sides of the cube.
Izvor: Međunarodna matematička olimpijada, shortlist 1969