a rectangle.
circle just did it on apex
an oval hemispere * * * * * The cross section must be 2-dimensional so it cannot be a hemispere - or hemisphere, even. I suggest the shape is lenticular: the shape of a convex lens (with equal radii of curvature).
No, a prism has flat sides. Triangular prisms are very common, but any polygon can be the cross section of a prism.
The cross section of a pyramid shrinks from the shape of the base down to a point as you move along its axis from the base to the apex. The cross section of a prism is constant along its axis.
A square.
The cross section of cylinder along its length (parallel to the axis of symmetry has the shape of a rectangle.
You cannot have a 2d cylinder. The 2d cross section will depend on the plane of the cross section.
a circle
a rectangle.
If the cylinder is standing on its flat face, the horizontal cross section is a circle. Otherwise, it is a line or a rectangle.
An ellipse or a rectangle, depending on how you cut it.
Holding the knife at different angles, you could cut a cylinder and get a circle, an ellipse, or a rectangle.
It will be a rectangle
A cylinder is a three dimensional shape with a uniform circular cross section and a finite length.
In Geometry, cross-section is the shape made when a solid is cut through by a plane. The cross section of a circular cylinder is a circle. * * * * * There are also cross-sections that are ellipses or rectangles.
circle just did it on apex