Cone

A cone is a basic shape in geometry . Several things have also been called cones on accountof their shape:

• An ice cream cone is a container for ice cream , shaped like an inverted cone open at its base. It is often made of edible pastry .
• The scaly fruit -like reproductive bodies of certain plants , especially pines and cycads ,are called cones: see conifer , conifer cone , and pinophyta .
• A volcanic cone is a mountain formed by materialejected from a volcanic vent .
• In relativity , the light cone of an event consists of all spacetime eventsthat can interact with it.
• In vertebrate anatomy , a cone cell is a type of light-sensitive cell found along with rods in the retina of the eye .
• In ceramics manufacture , a cone is a conical or pyramidal mineral stick that is used to gauge the temperature of an oven .

The word cone and its derivatives also have several specialized meanings in mathematics :

• In geometry , cone is often used informally for conical surface , usually a right circular one; see cone (geometry) .
• Also in geometry , the cone of an arbitrary set X means the union of all line segments connecting afixed 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 linearcombinations of those vectors with non-negative coefficients.
• In descriptive geometry , "conicalprojection" is another name for the perspectiveprojection .
• 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 thesurface of a cone (more precisely, a conical surface ) by an arbitraryplane.

• Traffic cones are plastic, cone shaped, objects that are usually usedto restrict motorists access during construction work.