Five faces, in all.
3D = Pyramid 2D = Triangle
Yes. Just like a square is 2D.
A flat (2D) shape triangle has 3 straight edges. A triangular pyramid has 6 straight edges. A square pyramid has 8 straight edges. (Note, some vertical edges have already been counted as you move from one face to the next.)
Heptagonal pyramid * * * * * No. A heptagonal pyramid has 8 vertices. You need a hexagonal pyramid or a pentagonal dipyramid for 7 vertices. Or, in 2d, a heptagon.
You cannot have a 2d pyramid - whether or not it is square based. The 2d cross section will depend on the plane of the cross section.
It is a 3 dimensional shape
It will look like a 2D equilateral triangle if it is a triangular based pyramid which is called a tetrahedron.
Five faces, in all.
4
It is NEITHER. A SQUARE is a PLAIN 2-dimensional figure . A PRISM & a PYRAMID are 3-dimensional objects.
a 2d square * * * * * A square has four sides. A side is not a face. A tetrahedron (triangular pyramid) has four faces.
The 2D polygon that has 11 vertices would be called an 11-gon. As for 3Dfigures, there are too many to name. One would be a decagon-based pyramid.
Square
No. A pyramid is a three-dimensional shape.
Pentagon 2d shape is a pentagon 3d object is a pyramid.
A prism is 3d and a pyramid is in 2d