Sujet : Re: Orange stacks
De : richard (at) *nospam* cogsci.ed.ac.uk (Richard Tobin)
Groupes : rec.puzzlesDate : 14. Jul 2025, 15:00:51
Autres entêtes
Organisation : Language Technology Group, University of Edinburgh
Message-ID : <10532ij$1dhk1$1@artemis.inf.ed.ac.uk>
References : 1 2 3 4
User-Agent : trn 4.0-test76 (Apr 2, 2001)
In article <
1052vlk$3dn0r$1@dont-email.me>,
David Entwistle <
qnivq.ragjvfgyr@ogvagrearg.pbz> wrote:
Then one shape (from the square pyramid) has a square top and bottom. It
looks to me like a truncated octahedron.
Top layer:
. . .
a b
. . .
c d
. . .
Middle layer:
e f g
. .
h i j
. .
k l m
Bottom layer:
. . .
n o
. . .
p q
. . .
If you consider the octahedron based on the square f, h, j, and l,
then the balls on the top and bottom layers do not fall on its faces -
in fact they are directly above and below the edges of the square: a
is directly above the midpoint of hf and n below it, forming a square
face.
There are in fact 6 square faces: abcd, nopq, ahnf, bfoj, djql, and
clph. And 8 triangular faces: abf, bdj, dcl, cah, nof, oqj, qpl, and
pnh. This is a cuboctahedron.
The second shape (from the triangular pyramid) is based exclusively on
equilateral triangles and is entirely regular [...]
I can see I'm going to have to buy some golf balls, or table tennis balls.
You will find that the second shape is also not what you think it is.
-- Richard