Rotate the the coordinate axes so that the projections of the speed V1 and v2 on the x axis are equal. Since #1 and #2 meet, their x coordinates are always equal. Also since #3 and #4 meet both #1 and #2 at different points, their x coordinates must be equal (to that of #1 and #2), too. Since their paths meet (this condition is redundent and can be deducted from the order of the events), they will arrive at the intersection at the same time. www.ddhw.com
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哈哈哈哈 O(∩_∩)O哈哈~ 好久不来了，不小心看了一眼自己主页，发现自动关联了自己以往发过的帖，点进这个看了一眼，笑个半死。。。敢情我当初还发过这么搞笑的东西啊，我自己完全不记得了 
雷达卡
发表于 2005-4-11 21:33:39