In the picture below, we have two parallel and distinct planes,, a circle R contained in and a straight r that intercepts , but not R:

For each point Ç Of region R, let's consider the segment , parallel to the straight line r :

Thus we have:

We call it cylinder, or circular cylinder, the set of all segments congruent and parallel to r.

Cylinder Elements

Given the following cylinder, consider the following elements:

  • bases: the center circles O and O'and lightning r

  • height: the distance H between the plans

  • generatrix: any end segment at the points of the base circumferences (for example, ) and parallel to the straight r

Cylinder Classification

A cylinder can be:

  • oblique circular: when the generatrices are oblique to the bases;

  • straight circular: when the geratrices are perpendicular to the bases.


The straight circular cylinder is also called the revolution cylinder because it is generated by the complete rotation of a rectangle on one side. Thus, the rotation of the ABCD rectangle by the side generates the following cylinder:

The straight contains the centers of the bases and is the axis of the cylinder.

Next: Cylinder Sections