A tangent is a straight line that just touches a curve, so the concept of "running the tangents" is to run the shortest distance possible by running straight from one curve to the next.
切线是一条直线,刚好接触到曲线,所以跑切线是从一个弯道跑到另一个最短的距离。
2
What I do at any point is project F to the tangent direction, I figure out how much F is going along my curve and then I sum these things together.
我所做的就是把F投影到切向量方向上,得出F沿着曲线的值,然后再把这些加起来。
3
Then actually there are ways you can use basically differentials and constrained partials to figure out what the tangent vector to the curve is and so on.