MATHEMATICS A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site torus The two-dimensional surface of a doughnut or inner-tube shape; the word comes from the Latin for "bulge" and was first used to describe the molding around the base of a column. One way to think of a torus is as a surface of revolution obtained by rotating a circle around an axis that lies in the plane of the circle but doesn't intersect the circle. The volume of a torus is π2r 2d and its surface area is 4π2rd, where r is the radius of the circle and d the distance of its center from the line. In the general case, where the shape being so rotated is any closed plane curve, the resulting surface is called a toroid. Although, as said above, the usual torus in three-dimensional space is shaped like a doughnut, the concept of the torus is extremely useful in higher dimensional space as well. Related category    • MATHEMATICS Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP