我个人比较喜欢用这个工具，而不是将路径转换为选区的方法，因为这样我就不需要去调整控制点和切线，尽管这中方法意味着更多地敲击鼠标。

I personally prefer this tool over the paths approach to selection because I don't have to adjust any control points and tangents, even though it means a lot more clicks.

youdao

如果我们画的Q点足够接近P点，就可以正确地画出切线了。

And, if we draw it close enough, then that's gonna be the correct line.

youdao

在射影几何的范畴内，全面地论述了两二次曲线的公有点和公切线的图解问题。

This paper deals with the graphics of the intersections and common tangents of two conics according to projective geometry .

youdao