ورلڈپیڈیا:Today's featured list/March 14, 2025
Equilateral square pyramid
Equilateral square pyramid
In geometry, there are 92 Johnson solids, which are convex polyhedra in which all faces are regular polygons. The definition of a Johnson solid, according to some authors, excludes uniform polyhedra (which include Platonic solids, Archimedean solids, prisms and antiprisms). They are named after the American mathematician Norman Johnson, who published a list of 92 non-uniform Johnson polyhedra in 1966; his list begins with the equilateral square pyramid (pictured), an example of a elementary polyhedron. His conjecture that the list was complete and no other examples of Johnson solids existed was proven by the Russian-Israeli mathematician Victor Zalgaller in 1969. (Full list...)