Geometrically, this "great" polyhedron has a polygonal base & sides which come to a common vertex
In geometry, a pyramid is defined as a 
polyhedron made by connecting a polygonal base (a two-dimensional shape... [DOC] [TLE] Names of Geometric ShapesWith Pictures | Owlcation [PAR] Aug 29, 2016 ... A common arch shape is a half-circle attached to a rectangle.