# Cylinder

## DEFINITION

A three-dimensional surface generated by a straight line (a generatrix) intersecting and moving along a closed plane curve (the directrix) while remaining parallel to a fixed straight line that is not on or parallel to the plane of the directrix. The portion of such a surface bounded by two parallel planes and the regions of the planes bounded by the surface. A solid bounded by two parallel planes and such a surface, especially such a surface having a circle as its directrix. Or a cylindrical vessel or object. Generally refers to a right cylinder ? having end planes both parallel and at 90 to the generatrix. Calculate volume of a right cylinder as pi (3.14159) times the radius squared times the length of the generatrix. The surface area of a right cylinder (including the circular ends) is 2 times pi times the radius times the product of the radius plus the length of the generatrix. The surface area of the lateral area (not including the circular ends) of a right cylinder is 2 times pi times the radius times the length of the generatrix. Canisters, drums, and rolling pins are typically cylindrical in form. Any of several parts of a printing press that rotate, especially the one that carries the paper. In archaeology, a cylindrical stone or clay object with an engraved design or inscription. (pr. SI-lən-dər)Examples: Mesopotamia, Cylinder seal and modern impression: hunting scene, 2250-2150 BCE, Late Akkadian period, chert, height 1.1 inches (2.8 cm), Metropolitan Museum of Art, NY.