Right Circular Cone Basics

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The following figure shows an example of a right circular cone:

Circular cross-section of cone

Note that the cross section of this cone is circular. This means that if you cut the cone anywhere with a horizontal plane, you will get a circular cross-section:

Cross-section of cone is circle

Also, the axis of the cone is perpendicular to the base, and hence it is right:

Cone's axis perpendicular to base

The following figure shows a cone which is right but not circular (the cross-section is elliptical):

Cone's cross-section is elliptical

The figure below shows a cone which is circular but not right (the axis is not perpendicular to the base):

Cone's axis not perpendicular to base

From now on, we will discuss only right circular cones, and we will refer to them as simply cones. The dimensions of a cone can be specified by two parameters: the radius \(r\)of the base or the flat surface, and the height \(h\) of the cone, as shown below.

Radius, height of right circular cone

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