Talk:Pentagonal trapezohedron

Pyramids?
I think that the sentence "The basic shape is two five-sided pyramids stuck together on their pentagonal face, one rotated by 36 degrees" is quite confusing and inaccurate; pyramids have triangular faces. Thus you cannot obtain a pentagonal trapezohedron just by "sticking together" two pyramids, though this seems suggestive. You would rather have to intersect them. fudo (questions?) 13:00, 13 April 2007 (UTC)


 * I think you're right. A geometrically exact explanation would be two pentagonal pyramids connected with a pentagonal antiprism between. At least that gives the volume. You then must merge triangle pairs to make the kite faces. Tom Ruen 19:14, 13 April 2007 (UTC)


 * Wouldn't that be an icosahedron? Double sharp (talk) 13:44, 17 August 2009 (UTC)


 * It would if the triangle faces are not parallel and not merged into kite faces. Tom Ruen (talk) 23:36, 22 August 2009 (UTC)

Different Format for Ten-Sided Dice
At the time of composing this message, I have eighteen ten-sided dice in front of me. Five of the eighteen use an alternative format. The sum of opposite faces equal 11 (with face marked 0 being valued as 10), and an order of 0, 4, 8, 6, 2, 1, 7, 3, 5, and 9 (following the same format as the explination for the "traditional" d10 configuration posted in this article). Is anyone aware of where this alternative dice format comes from, or what logic was used to dictate the order of the face values other than the sum of 11? The "side" containing 0, 8, 2, 7, and 5 has a sum of 32, while the other half containing 4, 6, 1, 3, and 9 has a sum of 23. Is this intentional because of the similarity of "32" and "23?"

Should information regarding this alternative format be posted to the main article? 64.229.1.106 (talk) 21:36, 24 July 2012 (UTC)


 * I don't know anything about positioning digits on dice, and it makes sense on even-sided dice that opposite sides should be reversed low/high, and perhaps there's other ideas. It seems like all the dice information is better placed at dice or dice, and ideally documented with sources. Tom Ruen (talk) 21:57, 24 July 2012 (UTC)
 * Along those lines I've often wondered about die with ten active faces and as many null (or "n/a/" faces as it took which would be symmetrical and roll true. I've never seen any, and I'm not even sure if such is geometrically possible. If there's a proof that it isn't, that should be added to the article. I'll look. kencf0618 (talk) 14:04, 22 December 2023 (UTC)
 * I reckon the fairest arrangement of numbers on dice is that which minimizes the difference between hemispheres. A couple of years ago I searched for arrangements that minimize the distance of the "center of mass" of the digits, which is not quite the same thing but close enough.  By this criterion, the two best arrangements for D10 are 0285364179 and 0582367149 (reading around the fivefold axis, alternating upper and lower faces). —Tamfang (talk) 08:35, 2 January 2024 (UTC)

Historical Error
RuneQuest was not the first published RPG to make use of d10's/d20's to generate percentages; That distinction actually goes to Dungeons and Dragons. Supplement 1 - Greyhawk added the thief class, with it's thief skills rated with perentages, and a number of other percentile rolls. Likewise, the pentagonal trapezohedron was not shipping from Chaosium until after 1980 - their games shipped with 3 or 4 d6 cubes, and a pair of icosahedron d20's well into the mid 80's, including ElfQuest and RuneQuest 3rd ed. They were the early 0-9 twice type in my RQ3 boxed set. And, despite using other dice (d4, d8), Chaosium didn't ship those. The first game with which i got a pentagonal trapezoedron was the 1981 Moldvay edition of D&D. Wfh (talk) 05:40, 12 April 2013 (UTC)
 * Well, that whole paragraph is unsourced, so it's fair game to edit. 24.12.74.21 (talk) 11:51, 12 April 2013 (UTC)