A378207 Decimal expansion of the midradius of a triakis tetrahedron with unit shorter edge length.

5, 8, 9, 2, 5, 5, 6, 5, 0, 9, 8, 8, 7, 8, 9, 6, 0, 3, 6, 6, 7, 3, 7, 0, 3, 0, 1, 7, 5, 4, 0, 4, 0, 8, 6, 6, 0, 7, 0, 6, 9, 6, 6, 1, 4, 7, 4, 0, 3, 9, 5, 0, 3, 0, 4, 9, 0, 2, 8, 3, 2, 2, 4, 1, 6, 2, 8, 0, 5, 1, 9, 9, 3, 5, 9, 2, 1, 1, 2, 6, 6, 1, 8, 7, 6, 6, 1, 4, 7, 2

Offset: 0

Author

Paolo Xausa, Nov 21 2024

Keywords

• nonn
• cons
• easy

Comments

The triakis tetrahedron is the dual polyhedron of the truncated tetrahedron.

Examples

			0.589255650988789603667370301754040866070696614740...
		

Links

• Index entries for algebraic numbers, degree 2.

Crossrefs

Cf. A378204 (surface area), A378205 (volume), A378206 (inradius), A378208 (dihedral angle).

Cf. A093577 (midradius of a truncated tetrahedron with unit edge).

Cf. A010524.

Programs

Mathematica

First[RealDigits[5/Sqrt[72], 10, 100]] (* or *)
First[RealDigits[PolyhedronData["TriakisTetrahedron", "Midradius"], 10, 100]]

PARI

5/sqrt(72) \\ Charles R Greathouse IV, Feb 11 2025

Formula

Equals 5/(6*sqrt(2)) = 5/A010524.