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1·Now, how do we get this unit vector?

那我们怎么得到这单位矢量呢？

2·It is not a unit vector.

它不是单位向量。

3·It's the unit vector in the vertical direction.

即竖直方向的单位向量。

4·So, that means this actually should be the unit vector.

这意味着这一项就是单位向量。

5·Now, another useful notion is the unit vector to the trajectory.

还有一个有用的概念就是轨道的单位矢量。

6·It has a hat because it's a unit vector, and t because it's tangent.

这上面有一个帽子表示它是单位矢量，T表示它是切线。

7·How to choose appropriate unit vector to establish new inequalities.

如何选择合适的单位向量来创建新的不等式。

8·Suppose A itself is the unit vector in the y direction B Then A dot B is what?

假设A是y方向上的,单位矢量,则是z方向上的单位矢量。，and，B，is，the，unit，vector，in，the，z，direction。,那A点B是多少呢？

9·A unit vector normal to the plane of t and n, which is the plane of curvature.

所构成的平面的单位向量，该平面为曲率所在的面。

10·You'll see why very soon, in such a way that the derivative is this given unit vector u hat.

你很快就会明白为什么,导数dr/ds等于给定的单位u向量。