the answer is triangle
It can be a quadrilateral or a triangle.
pentagonal pentahedron.
a solid figure with five plane surfaces
A quadrilateral is a plane or 2d figure with four sides. A 3d shape (object) has a name ending with -hedron, eg a tetrahedron which is a four sided 3d shape. A 3d quadrilateral has no meaning. Sides (edges) do exist in 3d shapes, but a more pertinent attribute is faces. Do you mean by "3d quadrilateral" a 3d shape which has a quadrilateral as a base and at most 4 or 5 other sides, ie a pentahedron (usually called a square pyramid) or a hexahedron (some types of which are called cuboids and cubes)? Please re-ask using consistent terminology, eg What is a 3d shape with one pair of parallel faces and 6 faces?
the answer is triangle
A 3d shape with 5 faces can be a square pyramid
It could be a pyramid with a quadrilateral base or a triangular prism. There are, of course, other related shapes that it could be.
A pentahedron is a 3-D shape and so, not surprisingly, a 3-D pentahedron is called a pentahedron!
pentahedron
I would say a square-based pyramid but there are many 3 dimensional shapes with 5 sides.* * * * *The generic name is a pentahedron.
It can be a quadrilateral or a triangle.
It can be a quadrilateral or a triangle.
It can be a quadrilateral or a triangle.
A pentahedron.
An example of a common five faced three dimensional shape is the square pyramid. There are no three dimensional shapes with five edges.
It is a pentahedron. One example of an irregular pentahedron is the 4-sided pyramid.