Yes, a polyhedron is only made up of one base which is bordered by straight lines. Each face is in fact a polygon, a closed shape in the flat 2-dimensional plane made up of points joined by straight lines.
A tetrahedron.
Tetrahedron
It depends on which method of tag you are playing
a base
Tetrahedron
pyramid .
A tetrahedron.
Tetrahedron
A polyhedron has only polygonal faces and any one of them can be considered a base. Therefore a polyhedron with 0 bases cannot exist.
It is a pentagon.
It is a pentagon.
A cone.
Yes. A base on a polyhedron is a face and a base on a polygon is a side.
It depends on which method of tag you are playing
This is a "trigonal pyramid" or "tetrahedron."
That seems to fit the description of a pyramid
a base