Different understandings of what that piece means gives you different values, and that's a bit of a problem.

应该是半径为1角度为,弧度为2比圆周率的一半，稍微多一点。

麻省理工公开课 - 计算机科学及编程导论课程节选

We'll adapt the convention that we'll measure angle in a radian.

我们要适应它,以后都用弧度来表示角的大小

耶鲁公开课 - 基础物理课程节选

But we like to measure angle in radians.

但是我们喜欢用弧度来衡量角度大小

耶鲁公开课 - 基础物理课程节选

How many people know about radians?

有多少人知道弧度

耶鲁公开课 - 基础物理课程节选

Okay. For those who have not seen a radian, it's just another way to measure angle with the understanding that a full circle, which we used to think is 360 degrees, So a radian is roughly 60 degrees.

我想告诉那些还不懂弧度制的同学,这是衡量角度的另一种方法,理解起来是这样的,对于一个整圆,也就是我们之前所说的360°,所以1弧度大约是60°

耶鲁公开课 - 基础物理课程节选