A square.
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.
A cross section of a cylinder along its length is called a rectangle. When a cylinder is cut along its length, the resulting shape is a rectangle with a length equal to the circumference of the cylinder and a height equal to the height of the cylinder. The area of this rectangle represents the lateral surface area of the cylinder.
A square.
The shape of a transverse cross section of a cylinder is a circle.
The cross section of cylinder along its length (parallel to the axis of symmetry has the shape of a rectangle.
The 2D parallel shape that represents a cross section of a cylinder is a circle. When a cylinder is sliced parallel to its base, each cross section reveals a circular shape, regardless of where the cut is made along the height of the cylinder. This circular cross section maintains the same diameter as the bases of the cylinder.
You cannot have a 2d cylinder. The 2d cross section will depend on the plane of the cross section.
a circle
a rectangle.
The shape of the cross section taken perpendicular to the base of a cylinder is a circle. This circular cross section is consistent regardless of the height at which the cut is made, as long as the cut is perpendicular to the axis of the cylinder. The radius of the circle corresponds to the radius of the cylinder's base.
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.
A cylinder is a 3D shape that has the same cross-section along its entire length. This means that if you slice the cylinder parallel to its bases, each cross-section will be identical to the others. Other examples include prisms, where the cross-section is a constant polygon along its height.