# The Cylinder

Cylinder is a solid bounded by a closed cylindrical surface and two parallel planes.

**Properties of a cylinder**

- The bounding cylindrical surface of a cylinder is called the
*lateral surface*, and the two bounding parallel planes are called the*bases*. The area of the lateral surface is denoted by A_{L}and the area of the base is denoted by A_{b}. - The bases of a cylinder are equal.
- The
*altitude*of the cylinder is the perpendicular distance between the bases. It is denoted by h. - Every section parallel to the base is equal to the base.
- Any two parallel sections, neither of which cuts a base are congruent.
- The
*right section*is perpendicular to the axis of the cylinder. The area of the right section is denoted as A_{R}. *Axis*of the cylinder is the line that connects the centroids of bases. The length of the axis is equal to the length of the element, it is deoted as L.- For right cylinder, the area of the right section is equal to the area of the base and the length of the axis is equal to the altitude.

**Name of a Cylinder**

The name of a cylinder is according to the shape of its base. If the base is ellipse, the cylinder is called elliptical cylinder, and if circle, it is called circular cylinder. The most common type of cylinder is the right circular cylinder.

**Formulas for Cylinder**

$V = A_R \, L = A_b \, h$

$A_L = P_R \, L$

V = volume of the cylinder

A

_{R}= area of the right section

L = length of the lateral side

A

_{b}= area of the base

h = altitude

A

_{L}= area of the lateral side

P

_{R}= perimeter of the base

Note that for right cylinder, A_{R} = A_{b} and L = h.