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In some areas of geometry and topology the term cylinder refers to what has been called a cylindrical surface. A cylinder is defined as a surface consisting of all the points on all the lines which are parallel to a given line and which pass through a fixed plane curve in a plane not parallel to the given line. [ 12 ]
N-shape, the shape that resembles the capital letter N (interchangeable with the Z-shape) O-shape, the shape that resembles the capital letter O. O-ring; P-shape, the shape that resembles the capital letter P. P-trap, a P-shaped pipe under a sink or basin; Pi-shape, the shape that resembles the Greek capital letter Π. Π topology in electronic ...
A common definition used in digital image processing (image analysis) for characterizing 2-D shapes is: Roundness = Perimeter 2 / 4 π × Area . This ratio will be 1 for a circle and greater than 1 for non-circular shapes. Another definition is the inverse of that: Roundness = 4 π × Area / Perimeter 2 ,
It is instead often topped with an inverted frustum of a shallow cone or a cylindrical band of carvings. It is often referred to as the masculine order because it is represented in the bottom level of the Colosseum and the Parthenon, and was therefore considered to be able to hold more weight. The height-to-thickness ratio is about 8:1.
[121] The Shah described Cyrus as the first ruler in history to give his subjects "freedom of opinion and other basic rights". [121] In 1968, the Shah opened the first United Nations Conference on Human Rights in Tehran by saying that the Cyrus Cylinder was the precursor to the modern Universal Declaration of Human Rights .
A zoetrope is a cylindrical variant of the phénakisticope, an apparatus suggested after the stroboscopic discs were introduced in 1833. The definitive version of the zoetrope, with replaceable film picture film strips, was introduced as a toy by Milton Bradley in 1866 and became very successful.
Geometry (from the Ancient Greek: γεωμετρία; geo-"earth", -metron "measurement") arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ().
It is an example of many classes of polyhedra: Platonic solid, regular polyhedron, parallelohedron, zonohedron, and plesiohedron. The dual polyhedron of a cube is the regular octahedron . The cube is the three-dimensional hypercube , a family of polytopes also including the two-dimensional square and four-dimensional tesseract .