题目内容
如图,正方形ABCD的边长为3,点E,F分别在边AB,BC上,AE=BF=1,小球P从点E出发沿直线向点F运动,每当碰到正方形的边时反弹,反弹时反射角等于入射角.当小球P第一次碰到BC边时,小球P所经过的路程为 ;当小球P第一次碰到AD边时,小球P所经过的路程为 ;当小球P第n(n为正整数)次碰到点F时,小球P所经过的路程为 .
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试题分析:根据已知中的点E,F的位置,可知入射角的正切值为
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由勾股定理可以得出EF=
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∴当小球P第一次碰到AD边时,小球P所经过的路程为:
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∴当小球P第2次碰到点F时,小球P所经过的路程为:
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当小球P第3次碰到点F时,小球P所经过的路程为:
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当小球P第4次碰到点F时,小球P所经过的路程为:
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……
当小球P第n(n为正整数)次碰到点F时,小球P所经过的路程为:
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