MathDB

5

Part of 1973 Poland - Second Round

Problems(1)

all faces acute in tetrahedron with AB = CD , AC = BD, AD = BC

Source: Polish MO Second Round 1973 p5

9/8/2024
Prove that if in the tetrahedron ABCD ABCD we have AB=CD AB = CD , AC=BD AC = BD , AD=BC AD = BC , then all faces of the tetrahedron are acute-angled triangles.
geometry3D geometrytetrahedron