Bipyramids

In geometry, a bipyramid, dipyramid, or double pyramid is a polyhedron formed by fusing two pyramids together base-to-base. The polygonal base of each pyramid must therefore be the same, and unless otherwise specified the base vertices are usually coplanar and a bipyramid is usually symmetric, meaning the two pyramids are mirror images across their common base plane. When each apex (, the off-base vertices) of the bipyramid is on a line perpendicular to the base and passing through its center, it is a right bipyramid; otherwise it is oblique. When the base is a regular polygon, the bipyramid i

Platonic solid

bipyramid over a triangle

third of the infinite set of face-transitive bipyramids

Johnson solid

Johnson solid

Johnson solid

polyhedron constructed by elongating a bipyramid by inserting an antiprism between its halves

polyhedron constructed by inserting a prism between the halves of a bipyramid

polyhedron formed from two hexagonal pyramids joined at their bases