The radian is a of angle used in the higher mathematics.  The magnitude of an angle α is one radian, if the arc corresponding the angle α as a central angleMathworldPlanetmath of a circle is equally long as the radius of the circle.  Thus, a radian is equal to 180π , minutes and seconds approximately 57o 17 44.80625′′.

In degrees, a circle has 360 degrees, while in radians a circle has 2π radians. In fact, many angles of equilateral polygonsMathworldPlanetmath are equal to a multiple of π divided by some integer: for example, the interior angleMathworldPlanetmath of an equilateral triangleMathworldPlanetmath’s vertex is π3, while the interior angle of an equilateral pentagon’s vertex is 3π5.

Title radian
Canonical name Radian
Date of creation 2013-03-22 14:48:58
Last modified on 2013-03-22 14:48:58
Owner PrimeFan (13766)
Last modified by PrimeFan (13766)
Numerical id 7
Author PrimeFan (13766)
Entry type Definition
Classification msc 51M04
Synonym absolute unit of angle
Related topic SolidAngle