Acronym etripy, J7
Name elongated triangular pyramid
 
 © ©
Vertex figure [33], [32,42], [3,42]
General of army (is itself convex)
Colonel of regiment (is itself locally convex)
Dihedral angles
  • between {3} and {4} (at tet,trip-join):   arccos(-sqrt(8/9)) = 160.528779°
  • between {3} and {4} (at bottom):   90°
  • between {3} and {3}:   arccos(1/3) = 70.528779°
  • between {4} and {4}:   60°
Confer
uniform relative:
tet   trip  
related Johnson solids:
etidpy   autip  
general polytopal classes:
Johnson solids   bistratic lace towers  
External
links
wikipedia   mathworld   quickfur  

While in etripy the trigonal base of trip gets augmented with a pyramid (tet), autip similarily would have the lacing square being augmented with a pyramid (squippy).


Incidence matrix according to Dynkin symbol

oxx3ooo&#xt   → height(1,2) = sqrt(3/8) = 0.612372
               height(2,3) = 1
(pt || pseudo {3} || {3})

o..3o..    | 1 * * | 3 0 0 0 | 3 0 0
.o.3.o.    | * 3 * | 1 2 1 0 | 2 2 0
..o3..o    | * * 3 | 0 0 1 2 | 0 2 1
-----------+-------+---------+------
oo.3oo.&#x | 1 1 0 | 3 * * * | 2 0 0
.x. ...    | 0 2 0 | * 3 * * | 1 1 0
.oo3.oo&#x | 0 1 1 | * * 3 * | 0 2 0
..x ...    | 0 0 2 | * * * 3 | 0 1 1
-----------+-------+---------+------
ox. ...&#x | 1 2 0 | 2 1 0 0 | 3 * *
.xx ...&#x | 0 2 2 | 0 1 2 1 | * 3 *
..x3..o    | 0 0 3 | 0 0 0 3 | * * 1

© 2004-2018
top of page