# solid angle

- an angle formed by three or more planes intersecting in a common point or formed at the vertex of a cone.

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## Origin of solid angle^{}

First recorded in 1695–1705

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

## solid angle

- a geometric surface consisting of lines originating from a common point (the vertex) and passing through a closed curve or polygon: measured in steradians

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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

## solid angle

- A three-dimensional angle, formed by three or more planes intersecting at a common point. Its magnitude is measured in steradians, a unitless measure. The corner of a room forms a solid angle, as does the apex of a cone; one can imagine an indefinite number of planes forming the smooth round surface of the cone all intersecting at the apex. Solid angles are commonly used in photometry.

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The American Heritage® Science Dictionary
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