For example, this is x=t, x=t^, you're going to have x=sin t and cos t and log t.

例如,这是x=t,x=t^,你还会遇到正弦,余弦,对数函数

耶鲁公开课 - 基础物理课程节选

Once you do that, I think it's fairly clear that it has got a y component that's given by cosine the x component is negative.

用了这个结论,我想很明显,y 分量由 cos φ 给出,它的 x 分量是负的

耶鲁公开课 - 基础物理课程节选