What is the shape of the cross-section formed when a cone intersects a

plane as shown in the drawing?

A circle is formed when a cone intersects a plane.

Explanation:

A cross section is the process where a surface is shown when a straight cut is made by something. In the question given when a cone is intersected by a plane horizontally the shape of the cross - section is a circle. On the other hand when the cone is intersected vertically by a plane the shape of the cross - section will be a triangle. Hence the shape of the cross section depends according to the cut.

Cross section is basically used to find what is there inside the object.