Acronym	trirp
Name	(degenerate) trigonal retroprism, retrograde trigonal antiprism
Circumradius	∞   i.e. flat in euclidean space
Dihedral angles	between {3} and {3}:   0°
Face vector	6, 12, 8
Confer	general antiprisms: n-ap   n/2-ap   n/d-ap   variations: xo3/2ox&#q
External links

Incidence matrix according to Dynkin symbol

s2s3/2s

demi( . .   .  ) | 6 | 1 1 2 | 1 3
-----------------+---+-------+----
      s2s   .    | 2 | 3 * * | 0 2
      s .   s2*a | 2 | * 3 * | 0 2
sefa( . s3/2s  ) | 2 | * * 6 | 1 1
-----------------+---+-------+----
      . s3/2s    ♦ 3 | 0 0 3 | 2 *
sefa( s2s3/2s  ) | 3 | 1 1 1 | * 6

or
demi( . .   . )              | 6 | 2 2 | 1 3
-----------------------------+---+-----+----
      s2s   .  &  s .   s2*a | 2 | 6 * | 0 2
sefa( . s3/2s )              | 2 | * 6 | 1 1
-----------------------------+---+-----+----
      . s3/2s                ♦ 3 | 0 3 | 2 *
sefa( s2s3/2s )              | 3 | 2 1 | * 6

starting figure: x x3/2x

s2s6/2o

demi( . .   . ) | 6 | 2 2 | 1 3
----------------+---+-----+----
      s2s   .   | 2 | 6 * | 0 2
sefa( . s6/2o ) | 2 | * 6 | 1 1
----------------+---+-----+----
      . s6/2o ) ♦ 3 | 0 3 | 2 *
sefa( s2s6/2o ) | 3 | 2 1 | * 6

starting figure: x x6/2o

ss3/2ss&#x   → height = 0
(shorter version of {3} || {3})

demi( o.3/2o.    ) & | 6 | 2 2 | 1 3
---------------------+---+-----+----
sefa( s.3/2s.    ) & | 2 | 6 * | 1 1
      ss   ..&#x   & | 2 | * 6 | 0 2
---------------------+---+-----+----
      s.3/2s.      & ♦ 3 | 3 0 | 2 *
sefa( ss3/2ss&#x )   | 3 | 1 2 | * 6

starting figure: xx3/2xx&#x

ss6/2oo&#x   → height = 0
(shorter version of {3} || {3})

demi( o.6/2o.    ) & | 6 | 2 2 | 1 3
---------------------+---+-----+----
sefa( s.6/2o.    ) & | 2 | 6 * | 1 1
      ss   ..&#x     | 2 | * 6 | 0 2
---------------------+---+-----+----
      s.6/2o.      & ♦ 3 | 3 0 | 2 *
sefa( ss6/2oo&#x )   | 3 | 1 2 | * 6

starting figure: xx6/2oo&#x