# radius vector

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## radius vector

(**vek**-ter) The line, of length

*r*, joining a point on a curve to a reference point, such as the origin in spherical and cylindrical coordinate systems. In planetary motion the radius vector is the line between the position of a planet and the focus of its orbit, i.e. the Sun's position. See also Kepler's laws.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

The following article is from

*The Great Soviet Encyclopedia*(1979). It might be outdated or ideologically biased.## Radius Vector

The radius vector of an arbitrary point in space is the vector drawn to the point from some fixed point, which is called the pole. If the origin of a rectangular Cartesian coordinate system is selected as the pole, then the projections of the radius vector of a point *M* on the coordinate axes coincide with the coordinates of *M*.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

## radius vector

[′rād·ē·əs ‚vek·tər] (astronomy)

A line joining the center of an orbiting body with the focus of its orbit located near its primary.

(mathematics)

The coordinate

*r*in a polar coordinate system, which gives the distance of a point from the origin.McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.