短语词组短语Brachistochrone Curve 最速曲线;最速降线问题brachistochrone problem 最速降线问题;线问题problem of brachistochrone 最速降线的问题;最速降线问题The brachistochrone problem 最速落径问题brachistochrone with bounded curvature 界曲率最速降线 返回 brachistochrone