题干

如图,∠AOB=90°,OA=45cm,OB=15cm,一机器人在点B处看见一个小球从点A出发沿着AO方向匀速滚向点O,机器人立即从点B出发,沿直线匀速前进拦截小球,恰好在点C处截住了小球.如果小球滚动的速度与机器人行走的速度相等,那么机器人行走的路程BC是多少?

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答案(点此获取答案解析)

解:∵小球滚动的速度与机器人行走的速度相等,运动时间相等,
即BC=CA,设AC为xcm,则OC=(45-x)cm,由勾股定理可知OB2+OC2=BC2
又∵OA=45,OB=15,把它代入关系式152+(45-x)2=x2
解方程得:x=25.
答:如果小球滚动的速度与机器人行走的速度相等,那么机器人行走的路程BC是25cm.

同类题3

阅读下面四篇短文,从每题所给的A、B、C、D四个选项中选出最佳选项。

B

 

    Think of life as a game in which you are playing with five balls in the air. You name them work, family, health, friends and spirit and you keep all of them in the air. You will soon understand that work is a rubber ball. If you drop it, it will bounce back.  

    But the other four balls, family, health, friends and spirit, are made of glass. If you drop one of these, it will be broken and never be the same. You must understand that and try to have balance in your life. How ?  

    Don't look down on your worth by comparing yourself with others. It is because we are different and each of us is special.  

    Don't let other people set goals for you. Only you know what is best for yourself.  

    Don't give up when you still have something to give. Nothing is really over until the moment you stop trying.

    Don't be afraid of difficulties. It is by taking chances that we learn how to be brave.

    Don't shut love out of your life by saying it's impossible. The quickest way to receive love is to give it; the fastest way to lose love is to hold it too tightly; the best way to keep love is to give it wings.  

    Don't run through life so fast that you forget not only where you've been, but also where you are going.  

    Don't be afraid to learn. Knowledge is weightless. It's a treasure you can always carry easily.  

    Don't use time or words carelessly. You can't get them back. Yesterday is history, tomorrow is a mystery*, and today is a gift; that's why we call it “the present”. Life is not a competition, but a trip, step by step.