Hexagonal bipyramid bipyramid has a plane of symmetry (which is horizontal in the figure to the right) where the bases of the two pyramids are joined. This plane is a regular hexagon. There are also six planes of symmetry crossing through the two apices. These planes are rhombic and lie at 30° angles to each other, perpendicular to the horizontal plane. It can be drawn as a tiling on a sphere which also represents the fundamental domains of [3,2], *322 dihedral symmetry: The hexagonal bipyramid, dt{2,6}, can be in sequence truncated, tdt{2,6} and alternated (snubbed), sdt{2,6}: The "hexagonal bipyramid", dt{2,6}, can be
How many angels can dance on the head of a pin? How many angels can dance on the head of a pin? The question "How many angels can dance on the head of a pin?" (alternatively ""How many angels can stand on the "point" of a pin?"") is a reductio ad absurdum of medieval scholasticism in general, and its angelology in particular, as represented by figures such as Duns Scotus and Thomas Aquinas. It is first recorded in the 17th century, in the context of Protestant apologetics. The question has also been linked to the fall of Constantinople, with the imagery of scholars debating about minutiae while the Turks besieged the