The radian (symbol rad) is the unit for measuring angles, and is the standard unit of angular measure used in many areas of mathematics.
The length of an arc of a unit circle is numerically equal to the measurement
in radians of the angle that it subtends; one radian is just under 57.3 degrees.
An arc of a circle with the same length as the radius of that circle subtends an
angle of 1 radian. The circumference subtends an angle of 2蟺 radians.
A complete revolution is 2蟺 radians (shown here with a circle of radius one and
thus circumference 2蟺).
Conversions
| Radians | Degrees |
|---|---|
| 0 | 0掳 |
| 蟺/12 | 15掳 |
| 蟺/6 | 30掳 |
| 蟺/4 | 45掳 |
| 1 | 57.3掳 |
| 蟺/3 | 60掳 |
| 蟺/2 | 90掳 |
| 蟺 | 180掳 |
| 2蟺 | 360掳 |