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A cylinder (from Greek κύλινδρος – ''kulindros'', "roller, tumbler"〔(κύλινδρος ), Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus〕) is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given straight line, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder. The surface area and the volume of a cylinder have been known since deep antiquity. ==Common use== In common use a ''cylinder'' is taken to mean a finite section of a ''right circular cylinder'', i.e., the cylinder with the generating lines perpendicular to the bases, with its ends closed to form two circular surfaces, as in the figure (right). If the ends are not closed, one obtains an open cylinder, whose surface is topologically equivalent to an open annulus. If the cylinder has a radius and length (height) , then its volume is given by : and its surface area is: * the area of the top * the area of the bottom * the area of the side (). Therefore, an open cylinder without the top or bottom has surface area (lateral area) :. The surface including the top and bottom as well as the lateral area is called a closed cylinder. Its surface area is :, where is the diameter. For a given volume, the closed cylinder with the smallest surface area has . Equivalently, for a given surface area, the closed cylinder with the largest volume has , i.e. the cylinder fits snugly in a cube (height = diameter).〔.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cylinder (geometry)」の詳細全文を読む スポンサード リンク
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