# steradian

[stuh-rey-dee-uh n]

- a solid angle at the center of a sphere subtending a section on the surface equal in area to the square of the radius of the sphere. Abbreviation: sr

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## Origin of steradian

Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

## steradian

- an SI unit of solid angle; the angle that, having its vertex in the centre of a sphere, cuts off an area of the surface of the sphere equal to the square of the length of the radiusSymbol: sr

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## Word Origin for steradian

C19: from stereo- + radian

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
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## steradian

[stĭ-rā′dē-ən]

- A unitless measure of solid angles. A solid angle projecting from the center of a sphere and cutting its surface has a measure ofsr2 steradians, where s is the surface area of the sphere cut out by the solid angle, and r is the radius of the sphere. See also radian.

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The American Heritage® Science Dictionary
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