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时钟是常见的计时工具,你可别小瞧它,小小的时钟里还藏着许多秘密呢。有一次,我遇到了一道有趣的钟表问题:钟面上的指针在7时的哪一时刻,时针与分针的夹角为60°?我立即拿起钟面模型拨了起来,几经尝试发现:7∶30时,时针与分针的夹角小于60°;7∶25时,时针与分针的夹角大于60°,就是找不到等于60°的时刻。我一脸无助地望着妈妈,妈妈神秘地对我说:“分针如兔子,时针如乌龟,它们上演着新版的‘龟兔赛跑’——追及问题。”听妈妈这么一比喻,我倒是有些思路了。“追及路程、追及时间、速度差”是追及问题的三要素,可是题目里一个都没说啊!
Clock is a common timekeeping tool, you do not look down upon it, there are many secrets hidden in the little clock yet. On one occasion, I encountered an interesting watch question: At what time was the hand on the clock face at 7 o’clock, the angle between the hour hand and the minute hand was 60 °? Immediately I picked up the clock face model and dial it. After several attempts, I found: At 7:30, the angle between the hour hand and the minute hand is less than 60 °. At 7:25 hour, the angle between the hour hand and the minute hand is greater than 60 °, which means that the moment equal to 60 ° can not be found. I look helplessly at my mom, my mom mysteriously said to me: “minute hand like a rabbit, the clock as a tortoise, they staged a new version of the” tortoise and the hare race “- to catch up with the problem.” “Listen to my mother such a metaphor, I have some ideas. ”Chasing the distance, chasing the time, speed difference " is the three elements to catch up with the problem, but the subject did not say ah!