A radian is the Anglesubtended by an arc of a circle whose length is just equal to the radius.
一弧度就是长度刚好等于半径的一段圆弧所对的圆心角。
2
We solved at the same time a pure mathematical problem by physical procedure i. e. calculating the solid anglesubtended by a circular plate to any point in the space.
同时,用物理学方法解决了圆盘面对空间任意点所张的立体角的计算问题。
3
The Anglesubtended at the center of a sphere by an area on its surface numerically equal to the square of the radius.