which 2d shape is a cross section of both a cylinder and a pyramid
The 2D shape that is a cross section of both a cylinder and a pyramid is a circle.
why
A cylinder is made up of two parallel circular bases connected by a curved surface. When you slice through a cylinder parallel to its bases (creating a cross section), you get a circle.
A pyramid, on the other hand, has a polygonal base (such as a triangle, square, pentagon, etc.) that connects to a single point called the apex. When you slice through a pyramid perpendicular to the base (creating a cross section), you get a shape that matches the shape of the base.
So, in the case of a cylinder and a pyramid, the common cross section shape would be a circle since cutting either shape in a certain way would result in a circular cross section.