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.
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
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