A polygon is a 2-dimensional figure, a solid is 3-dimensional.
A vertex is the point where three or more edges of a solid figure meet.
It is not a solid figure because an icosagon is a polygon with 20 sides
Such a figure is a pyramid.
No. A polygon is a plane figure - i.e. it is 2-dimensional A cone is a solid figure - i.e it is 3-dimensional
octagonal prism (i guessed)