如图所示，菱形
的边长为6厘米，
．从初始时刻开始，点
、
同时从
点出发，点以1厘米/秒的速度沿
的方向运动，点以2厘米/秒的速度沿
的方向运动，当点运动到
点时，、两点同时停止运动，设、运动的时间为
秒时，
与
重叠部分的面积为
平方厘米（这里规定：点和线段是面积为0的三角形），解答下列问题：
（1）点、从出发到相遇所用时间是 秒；
（2）点、从开始运动到停止的过程中，当是等边三角形时
的值是 秒；
（
3）当0≤≤6时，求与之间的函数关系式．
（1）6．······················································································································· 3分
（2）8．······················································································································· 3分
（3）①当0
时，
． ·········································· 3分
②当3
时，
=
········································································································· 3分