User:Boris Tsirelson/Sandbox1: Difference between revisions

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In [[Euclidean geometry]], a '''line''' (sometimes called, more explicitly, a '''straight line''') is an abstract concept that models the common notion of a curve that does not bend, has no thickness and extends infinitely in both directions.
"Some products — such as new drugs and complex medical devices — must be proven safe and effective before companies can put them on the market" [http://www.fda.gov/NewsEvents/ProductsApprovals/ucm106288.htm About FDA Product Approval].
 
It is closely related to other basic concepts of geometry, especially, distance: it provides the shortest path between any two of its points. In space it can also be described as the intersection of two planes.
 
Assuming a common (intuitive, physical) idea of the geometry of a plane, "line" can be defined in terms of distances, orthogonality, coordinates etc.
 
In a more abstract approach ([[vector space]]s) lines are defined as one-dimensional affine subspaces.
 
In an axiomatic approach, basic concepts of elementary geometry, such as "point" and "line", are undefined primitives.

Revision as of 06:13, 27 May 2010

"Some products — such as new drugs and complex medical devices — must be proven safe and effective before companies can put them on the market" About FDA Product Approval.

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