Noun

radius (plural radii or radiuses)

  1. (anatomy) The long bone in the forearm, on the side of the thumb.
  2. (zoology) The lighter bone (or fused portion of bone) in the forelimb of an animal.
  3. (geometry) A line segment between any point on the circumference of a circle and its center/centre.
  4. (geometry) The length of this line segment.

Related terms

From Wiktionary under the GNU Free Documentation License.
Sun Aug 15 19:05:33 2010

In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter.

More generally — in geometry, science, engineering, and many other contexts — the radius of something (e.g., a cylinder, a polygon, a mechanical part, a hole, or a galaxy) usually refers to the distance from its center or axis of symmetry to a point in the periphery: usually the point farthest from the center or axis (the outermost or maximum radius), or, sometimes, the closest point (the short or minimum radius). If the object does not have an obvious center, the term may refer to its circumradius, the radius of its circumscribed circle or circumscribed sphere. In either case, the radius may be more than half the diameter (which is usually defined as the maximum distance between any two points of the figure)

The inradius of a geometric figure is usually the radius of the largest circle or sphere contained in it. The inner radius of a ring, tube or other hollow object is the radius of its cavity.

The radius of a regular polygon (or polyhedron) is the distance from its center to any of its vertices; which is also its circumradius. The inradius of a regular polygon is also called apothem.

In graph theory, the radius of a graph is the minimum over all vertices u of the maximum distance from u to any other vertex of the graph.

The name comes from Latin radius, meaning "ray" but also the spoke of a chariot wheel. The plural in English is radii (as in Latin), but radiuses can be used, though it rarely is.

From Wikipedia under the GNU Free Documentation License
Fri Sep 3 02:30:00 2010

What is the radius of the circle described below?
Q. What is the radius of a circle centered on the circumference of a unit circle (radius=1), such that the portion of its area which is not common to the two circles is equal to the area of the unit circle? Algebra and trigonometry allows terms to be interpreted geometrically, which calculus does not. Very few can solve this in 3 days.
Asked by skeptic - Sat Jul 12 16:12:48 2008 - - 1 Answers - 0 Comments

A. If the area common to both circles is greater than zero, then the area of the unknown circle must be greater than the area of the unit circle, so the unknown radius must be greater than 1, and thus the unit circle must lie entirely within the unknown circle. So the area of the unknown circle consists of two equal areas, common and not common, each equal to pi. So pi(r^2) = 2pi r^2 = 2 r = square root of 2
Answered by Roger the Mole - Sat Jul 12 19:41:38 2008

What is the killing radius of an high explosive artillery shell ?
Q. I know it depends on the shell caliber, so lets say its 155mm. And does this killing radius mean that ALL the humans in this area will be KILLED ?
Asked by TheEmperor - Sat Mar 13 18:27:58 2010 - - 3 Answers - 0 Comments

A. Hello there emperor I am the surfer A large part of the killing power of artillery comes from shrapnel, little fragments of metal balls meant to expand within every direction destroying machines and causing dead and wounded From the surfer
Answered by thesurfer - Sat Mar 13 20:38:34 2010

How do I calculate the radius of the orbital associated with the energy levels E4 and E5 of the hydrogen atom?
Q. Also, what energies would be associated with these two energy levels? I calculated the energy levels to be -.85 and -.544 for E4 and E5 respectively with the formula E = (-13.6)(1/n2), however, what units is this? What is the formula/units for calculating radius? Thanks so much.
Asked by Dude - Tue May 4 21:00:38 2010 - - 1 Answers - 1 Comments

A. The -13.6 value is the energy at level 1 in eV, so your answers are in eV. The radius formula is r = N^2*a0/Z, where N is the orbit level number, a0 is the Bohr radius constant = 5.29E-11 m and Z is the atom proton number which = 1 for hydrogen. See the ref.
Answered by kirchwey - Wed May 5 00:28:39 2010

From Yahoo Answer Search: "radius"
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Radius To use any of the clipart images above including the thumbnail image in the top left corner just click and drag the picture to your desktop You may also control click Mac or right click

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Nodosauridae from the Smoky Hill Chalk Upper Cretaceous of western Kansas Kansas Academy of Science Transactions 108 1 2 15 21 See also Hamm and Everhart 2001 The right ulna and radius of a small nodosaur were recovered from the Smoky Hill Chalk Member Upper Santonian of the Niobrara Formation in October 2000 Based on the similarity of the specimen in comparison

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lack of rigidity was immediately apparent and I was only able to take fine cuts I also found that because the bar was flexing several passes were needed to take the spring out of the tool Rigidity of the cutter was a problem whilst flycutting the saddle base 2 February 2009 I was keen to see if I could finish machining the saddle using only my existing machine tools The 6 3

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Fri, 06 Aug 2010 03:24:27 GM

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