Definition:Angle/Unit/Radian
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Definition
The radian is a measure of plane angles symbolized either by the word $\mathrm{rad}$ or without any unit.
Radians are pure numbers, as they are ratios of lengths. The addition of $\mathrm{rad}$ is merely for clarification.
$1 \ \mathrm{rad}$ is the angle subtended at the center of a circle by an arc whose length is equal to the radius:
Value of Radian in Degrees
The value of a radian in degrees is given by:
- $1 \ \mathrm{rad} = \dfrac {180 \degrees} {\pi} \approx 57.29577 \ 95130 \ 8232 \ldots \degrees$
This sequence is A072097 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008).
Also see
Sources
- 2008: Ian Stewart: Taming the Infinite ... (previous) ... (next): Chapter $5$: Eternal Triangles
- For a video presentation of the contents of this page, visit the Khan Academy.