Radian

[reidiәn]

解释:

(noun.) 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).

阿纳托尔校对--From WordNet

解释:

(n.) An arc of a circle which is equal to the radius, or the angle measured by such an arc.

手打:内蒂

解释:

n. the angle subtended at the centre of a circle by an arc equal to the radius.

编辑:罗赞娜