Theory:

A cross-section may be a shape we get when cutting 3D figures by a plane.
Example:
Cross-section of a cone.
cone-and-circle.gif
There are two different types of the cross-section.
  1. Horizontal or parallel cross-section
  2. Vertical or perpendicular cross-section
  
Horizontal cross-section: A plane cuts the solid shape in the horizontal direction(parallel to the base).
 
Vertical cross-section: A plane cuts the solid shape in the vertical direction(perpendicular to the base).
 
Example:
The horizontal cross-section of the cylinder is a circle and the vertical cross-section of the cylinder is a rectangle.
 
Horizontal cross-sectionVertical cross-section
7-w300.png2-w300.png
 
Some of the \(3D\) shapes with its horizontal cross-section are given below.
pic9.png