Cone
A cone is a basic geometrical shape: see cone (geometry) . Several things have also been called "cones" on account of their shape:
The word cone and its derivatives also have several specialized meanings in mathematics :
In geometry ,
Also in geometry , the cone of an arbitrary set X means the union of all line segments connecting a fixed point to points of X . For exmple, this coning operation will turn a triangle into a tetrahedron .
In topology , too, coning may be applied to a topological space , e.g. to define the barycentric subdivision of a cell complex ; see cone (topology) .
In linear algebra , the convex cone of a set of vectors consists of all linear combinations of those vectors with non-negative coefficients.
In graph theory , a cone graph is a graph with a universal vertex (a vertex that is connected to all others vertices).
In descriptive geometry , "conical projection " is another name for the perspective projection .
In cartography , however, a conical projection maps the spherical surface of the Earth to a conical surface , that is then unrolled onto a plane.
A conic section is any curve obtained by cutting the surface of a cone (more precisely, a conical surface ) by an arbitrary plane.