An isosceles trapezium.
A regular tetrahedron (triangular pyramid).
A pentagonal pyramid.
I doubt it because no matter how big the base is, if you laid the triangles in to the position of the base (ex 4 triangles to a square base) they would have a larger area than the base shape
Yes. A polyhedron is a geometric shape with flat surfaces and straight edges, so a a pyramid with a rectangular base qualifies as a polyhedron. It is however not a regular polyhedron, which would require all the faces to be the same shape and size. To change your pyramid to a regular polyhedron you'd have to turn it into a tetrahedron.
A rectangular frustum.
It is the net of its solid shape. If the top of the pyramid is cut off parallel to the base, then it is a truncated pyramid, or a frustum.
It is the net of its solid shape. If the top of the pyramid is cut off parallel to the base, then it is a truncated pyramid, or a frustum.
Rectangle
Triangular.A pyramid has triangular faces
Most likely, a frustum of a sphere.Most likely, a frustum of a sphere.Most likely, a frustum of a sphere.Most likely, a frustum of a sphere.
A tri-lateral pyramid, also known as a regular tetrahedron.
A regular tetrahedron (triangular pyramid).
A circle.
A pentagonal pyramid.
I doubt it because no matter how big the base is, if you laid the triangles in to the position of the base (ex 4 triangles to a square base) they would have a larger area than the base shape
A frustum of a cone.
A rectangular frustum.