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Bang's theorem on tetrahedra

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20: 46:, and segments are drawn from the points of tangency to each vertex on the same face of the tetrahedron, then all four points of tangency have the same triple of angles. In particular, it follows that the 12 triangles into which the segments subdivide the faces of the tetrahedron form congruent pairs across each edge of the tetrahedron. It is named after A. S. Bang, who posed it as a problem in 1897. 138: 133: 65: 63:
Brown, B. H. (April 1926), "Theorem of Bang. Isosceles tetrahedra", Undergraduate Mathematics Clubs: Club Topics,
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On angles formed when a sphere is inscribed within a tetrahedron
8: 55: 7: 14: 79:10.1080/00029890.1926.11986564 1: 66:American Mathematical Monthly 102:Nyt Tidsskrift for Matematik 32:Bang's theorem on tetrahedra 160: 139:Euclidean solid geometry 100:"Opgaver til Løsning", 23: 22: 134:Theorems in geometry 34:states that, if a 24: 151: 118: 116: 97: 91: 89: 60: 159: 158: 154: 153: 152: 150: 149: 148: 124: 123: 122: 121: 108:(A): 48, 1897, 99: 98: 94: 62: 61: 57: 52: 17: 12: 11: 5: 157: 155: 147: 146: 141: 136: 126: 125: 120: 119: 117:, problem 266. 92: 73:(4): 224–226, 54: 53: 51: 48: 15: 13: 10: 9: 6: 4: 3: 2: 156: 145: 142: 140: 137: 135: 132: 131: 129: 115: 111: 107: 104:(in Danish), 103: 96: 93: 88: 84: 80: 76: 72: 68: 67: 59: 56: 49: 47: 45: 41: 37: 33: 29: 21: 105: 101: 95: 70: 64: 58: 31: 25: 44:tetrahedron 144:Tetrahedra 128:Categories 50:References 42:within a 40:inscribed 114:24528123 28:geometry 87:2299548 112:  85:  36:sphere 110:JSTOR 83:JSTOR 75:doi 38:is 26:In 130:: 81:, 71:33 69:, 30:, 106:8 90:. 77::

Index


geometry
sphere
inscribed
tetrahedron
American Mathematical Monthly
doi
10.1080/00029890.1926.11986564
JSTOR
2299548
JSTOR
24528123
Categories
Theorems in geometry
Euclidean solid geometry
Tetrahedra

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