A 3D shape with all straight edges and flat faces is a polyhedron. Other 3D shapes with least one curved surface are not polyhedra. A 3D shape with regular polygonal faces, meeting at equal angles, is ...

This media is in the public domain (free of copyright restrictions). You can copy, modify, and distribute this work without contacting the Smithsonian. For more information, visit the Smithsonian's ...

When stacking apples on a market stall, fruit sellers “naturally” adopt a particular arrangement: a regular pyramid with a triangular base. Scientists have now demonstrated that this arrangement is ...