radian
[rey-dee-uh n]
- the measure of a central angle subtending an arc equal in length to the radius: equal to 57.2958°. Abbreviation: rad
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Origin of radian
Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for radian
Historical Examples
Strob, strob, n. the angular velocity of one radian per second.
radian
- an SI unit of plane angle; the angle between two radii of a circle that cut off on the circumference an arc equal in length to the radius. 1 radian is equivalent to 57.296 degrees and π/2 radians equals a right angleSymbol: rad
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Word Origin
C19: from radius
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for radian
n.
"angle subtended at the center of a circle by an arc equal in length to the radius," 1879, from radius.
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Online Etymology Dictionary, © 2010 Douglas Harper
radian
(rā′dē-ən)- A unit of angular measure equal to the angle subtended at the center of a circle by an arc equal in length to the radius of the circle.
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The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
radian
[rā′dē-ən]
- A supplementary unit of the International System used in angular measure. One radian is equal to the angle subtended at the center of a circle by an arc equal in length to the radius of the circle, approximately 57°17′44.6″.
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The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.