11
Nonagon
An hexagonal prism would fit the given description
A decagon based pyramid. It is a hendecahedron but that can take many shapes. A nonagon based prism, for example.
A decahedron. Some decahedron shapes are a nonagon-based pyramid, an octagon based prism, or a pentagon based di-pyramid.
Nonagonal is a prefix. A nonagon is a nine sided polygon. A nonagonal prism, is a prism.
11
Nonagon
An hexagonal prism would fit the given description
A decagon based pyramid. It is a hendecahedron but that can take many shapes. A nonagon based prism, for example.
nonagon
A decahedron. Some decahedron shapes are a nonagon-based pyramid, an octagon based prism, or a pentagon based di-pyramid.
Because nonagon means 9 sides
Not a regular nonagon.
There are many possibilities. Some of them are: A nonagon-based pyramid. A hexagonal prism. A hexagonal dipyramid (two hexagon-based pyramids stuck together on their bases).
A nonagon has nine sides.
A nonagon