# Talk:Truncated tetrahedron

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Field: Geometry

## Cartesian coordinates

I agree that "even permutations" is non-obvious, but I didn't say "even permutations". How difficult is "an even number of minus signs"? —Tamfang 23:28, 2 May 2007 (UTC)

Well, I expanded it fully when I was trying to figure out the original less clear wording to build a VRML model. The list is short, and clear, so I prefered to have it explicit. I thought about mixing your wording and the list, but was too lazy. Can a compromise have both? Tom Ruen 05:12, 3 May 2007 (UTC)
Okay tried it. I actually thought it might be nice to show a transparent cube with truncated tetrahedron edges shown on it, but didn't take the time. Tom Ruen 05:15, 3 May 2007 (UTC)
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## Section on architecture

Maybe I'm wrong, but that section refers to truncated tetrahedrons as "tetrahedrons". Looking at the picture, I'm pretty sure that truncated tetrahedrons have eight faces, not four. Could someone change this bit? 4 T C 00:32, 24 January 2010 (UTC)

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## removed

I removed this from then openning, no references, no context for intro. Tom Ruen (talk) 02:27, 31 January 2010 (UTC)

If the truncated tetrahedron has unit edge lengths, its dual triakis tetrahedron has edge lengths $\frac{9}{5}$ and 3.
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## Friauf polyhedron?

Anyone want to research what these are? There are apparently 5 of them around an axis, implying a 6-6 dihedral angle of 72 degrees, versus 70d31'44" for semiregular form by Williams. Its linked on wikipedia at Complex_metallic_alloys

β-Al-Mg: 1168 atoms per unit cell, face centred cubic, atoms arranged in Friauf polyhedra.

The reference linked is [1], but many other matches on google. Tom Ruen (talk) 21:45, 28 March 2013 (UTC)

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Last modified on 28 March 2013, at 23:43