Chat with our AI personalities
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.
The following are some shapes having a square cross section: a cube, a cuboid, a square pyramid.
Depending on the inclination of the plane used for the cross-section, it could be a square, rectangle, trapezium, triangle.
It depends on the pyramid. If it is a square based pyramid, a horizontal plane will give a square cross section, a plane inclined by a rotation parallel to one of the base axes will give a rectangular cross section whereas a plane inclined by rotation along both basal axes will result in a parallelogram cross section. Not sure how you get a parallelogram from a pentagonal or hexagonal (etc) pyramid.
The vertical cross sections are trapezia or triangles. The horizontal cross sections are rectangles which are mathematically similar to the base.