Well-centeredness and Orthoschemes

Last time we looked at well-centered polytopes and I wondered whether a vertex-transitive polytope with well-centered \(j\)-faces would be completely well-centered. (For \(j=0\) or 1 the condition is trivial, since points and edges are always well-centered, so we’d have to require \(j=2\) at least.) This seems to be false. But why would I think this?

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Twisty Antiprisms

There’s an easy way to make antiprisms whose sides are isosceles triangles: take two congruent regular \(n\)-gons, rotate one so its vertices are halfway between the original positions (that is, by 1/(2n)-th of a circle), and lift one up. Unless you pick one particular height, you end up with isosceles triangles on the side. (There’s one height that gives you equilateral triangles.)

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