A nine-sided object is known as a nonagon.
Octagon.
A five sided 2 dimensional object is called a pentagon.
A 20 sided polygon is an 'icosagon'
Icosogon
A nine-sided object is known as a nonagon.
A 20-sided polygon is an icosagon.(see related link)
An icosagon is the name of the 20 sided polygon.
The name of a 20 sided polygon is Icosagon.
The name of a 20 sided polygon is Icosagon.
the name of a 20 sided 3d shape is called a icosahedron
Decagon.
octagon
Octagon.
hendecagon
the Greeks used prefexes up to ten, modernly we have sdded dodecagon for a twelvesided object and undecagon for an eleven sided object so the propor name would be a 27 sided object.
A hexakaidecagon (hexadecagon).