然后你将会一直绕另一辆车转，但当你从上面看，你们两个一直在向前行驶且你们的路径是凸形的。

You will then be making circles around the other car, but when seeing from above, both of you are driving forward all the time and your path will be convex.

youdao

反曲线饰纵断面部分为凹线，部分为凸形的檐口的线脚，尤用在古典建筑中。

A molding for a cornice, having a partly concave and partly convex curve in profile, used especially in classical architecture.

youdao

然后你将会一直绕这辆车转，但当你从上面看下来，会发现你们两个都在向前行驶并且你们的路径都是凸形的。

You will then be making circles around the other car, but when seen from above, both of you are driving forward all the time and your path will be convex.

youdao