Bang's Theorem

The lines drawn to the Vertices of a face of a Tetrahedron from the point of contact of the Face with the Insphere form three Angles at the point of contact which are the same threeAngles in each Face.

References

Brown, B. H. ``Theorem of Bang. Isosceles Tetrahedra.'' Amer. Math. Monthly 33, 224-226, 1926.

Honsberger, R. Mathematical Gems II. Washington, DC: Math. Assoc. Amer., p. 93, 1976.

• Radius Vector
• Radix
• Radon-Nikodym Theorem
• Radon Transform
• Radon Transform--Cylinder
• Radon Transform--Delta Function
• Radon Transform--Gaussian
• Radon Transform--Square
• Rado's Sigma Function
• Railroad Track Problem
• Ramanujan 6-10-8 Identity
• Ramanujan Constant
• Ramanujan Continued Fraction
• Ramanujan Cos/Cosh Identity
• Ramanujan-Eisenstein Series
• Ramanujan Function
• Ramanujan g- and G-Functions
• Ramanujan-Petersson Conjecture
• Ramanujan Psi Sum
• Ramanujan's Hypergeometric Identity
• Ramanujan's Hypothesis
• Ramanujan's Identity
• Ramanujan's Integral
• Ramanujan's Interpolation Formula
• Ramanujan's Master Theorem