摘要： 中...cm．长为1cm的线段在的边上沿方向以1cm/s的速度向点运动(运动前点与点重合)．过分别作的垂线交直角边于两点.线段运动的时间为s． (1)若的面积为.写出与的函数关系式(写出自变量的取值范围), (2)线段运动过程中.四边形有可能成为矩形吗?若有可能.求出此时的值,若不可能.说明理由, (3)为何值时.以为顶点的三角形与相似? 解:(1)当点在上时..． ．········································································ 2分 当点在上时.． ．·················································· 4分 (2).．． ．········································································ 6分 由条件知.若四边形为矩形.需.即. ． 当s时.四边形为矩形．································································· 8分 知.当s时.四边形为矩形.此时. ．··························································································· 9分 除此之外.当时..此时． .．．····························· 10分 .． 又.．········································ 11分 .． 当s或s时.以为顶点的三角形与相似．··················· 12分

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