radian

详细解释:n. 弧度
【计】 弧度
【化】 弧度
【医】 弧度

英语解释：

名词 radian:

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)同义词：rad