IMO Shortlist 1967 problem 2
Dodao/la:
arhiva2. travnja 2012. Prove this proposition: Center the sphere circumscribed around a tetrahedron which coincides with the center of a sphere inscribed in that tetrahedron if and only if the skew edges of the tetrahedron are equal.
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Prove this proposition: Center the sphere circumscribed around a tetrahedron which coincides with the center of a sphere inscribed in that tetrahedron if and only if the skew edges of the tetrahedron are equal.
Izvor: Međunarodna matematička olimpijada, shortlist 1967
Školjka 
