The radian is the standard unit of angular measure. An angle's measurement in radians is numerically equal to the length of a corresponding arc of a unit circle. One radian is equal to 57.3 degrees (when the arc length is equal to the radius).

In a half circle there are π radians, which is also 180°So: π radians =180°[br] [br]So: 1 radian=180°/π =57.2958...° (approximately)[br][br]To go from [b]radians to degrees[/b]: multiply by 180, divide by π[br]To go from [b]degrees to radians[/b]: multiply by π, divide by 180