What is the shape of a cross section made perpendicular to the base of a cone?

A cross section is the shape we get when cutting straight through an object.

The cross section of this object is a triangle.

It is like a view into the inside of something made by cutting through it.

This is a cross-section of a piece of celery.

Geometry

In geometry it is the shape made when a solid is cut through by a plane.

Example:

The cross section of this circular cylinder is a circle

We don't draw the rest of the object, just the shape made when you cut through.

Example:

The cross section of a rectangular pyramid is a rectangle

Cross sections are usually parallel to the base like above, but can be in any direction.

The vertical cross section through the center of this torus is two circles!

And the horizontal cross section is an annulus

More Examples of Cross Sections