# Definitions for **radian**ˈreɪ di ən

### This page provides all possible meanings and translations of the word **radian**

### Random House Webster's College Dictionary

ra•di•anˈreɪ di ən(n.)

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

**Category:**Math**Ref:**Abbr.: rad 2

#### Origin of **radian**:

1875–80

### Princeton's WordNet

radian, rad(noun)

the unit of plane angle adopted under the Systeme International d'Unites; equal to the angle at the center of a circle subtended by an arc equal in length to the radius (approximately 57.295 degrees)

### Wiktionary

radian(Noun)

In the International System of Units, the derived unit of plane angular measure of angle equal to the angle subtended at the centre of a circle by an arc of its circumference equal in length to the radius of the circle. Symbol: rad

**Origin:** From radi(us) + -an

### Webster Dictionary

Radian(noun)

an arc of a circle which is equal to the radius, or the angle measured by such an arc

### Freebase

Radian

The radian is the standard unit of angular measure, used in many areas of mathematics. An angle's measurement in radians is numerically equal to the length of a corresponding arc of a unit circle, so one radian is just under 57.3 degrees. The unit was formerly an SI supplementary unit, but this category was abolished in 1995 and the radian is now considered an SI derived unit. The SI unit of solid angle measurement is the steradian. The radian is represented by the symbol "rad" or, more rarely, by the superscript c. For example, an angle of 1.2 radians would be written as "1.2 rad" or "1.2c".

### The Standard Electrical Dictionary

Radian

The angle whose arc is equal in length to the radius; the unit angle.

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"radian." *Definitions.net.* STANDS4 LLC, 2014. Web. 17 Sep. 2014. <http://www.definitions.net/definition/radian>.