radian

American  

[rey-dee-uhn] / ˈreɪ di ən /

noun

Mathematics.

1. the measure of a central angle subtending an arc equal in length to the radius: equal to 57.2958°. rad

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radian British  

/ ˈreɪdɪən /

noun

1.  rad.  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 angle

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radian Scientific  

/ rā′dē-ən /

1. 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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Etymology

Origin of radian

First recorded in 1875–80; radi(us) + -an

Example Sentences

We create Figure 10 by choosing several input values close to with half of them less than and half of them greater than Note that we need to be sure we are using radian mode.

From Textbooks • Dec. 1, 2021

Radian measure is defined such that the angle associated with the arc of length 1 on the unit circle has radian measure 1.

From Textbooks • Mar. 30, 2016

In radian mode, In degree mode, Note that in calculus and beyond we will use radians in almost all cases.

From Textbooks • Feb. 13, 2015

This ratio, called the radian measure, is the same regardless of the radius of the circle—it depends only on the angle.

From Textbooks • Feb. 13, 2015

The torsion couple per radian was determined by preliminary experiments.

From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 4 "Grasshopper" to "Greek Language" by Various