数学实验中的最速落径问题

A,B是不在一条铅垂线上的两点，在链接A,B两点的所有光滑曲线中，找出一条曲线，使得初速度为零的质点，在重力的作用下，自A点下滑到B点所需的时间最短

-Mathematical experiment steepest drop Path problems A, B is not a vertical line of two points, the link A, B two points in all the smooth curve, to find a curve, the initial velocity of the particle is zero, gravity role, and since the point A to B points decline in the time required for the shortest