如图1,在矩形
中,
,点E,F分别为
,
边的中点.动点P从点E出发沿
向点D运动,速度为
,同时,动点Q从点F出发沿
向点B运动,速度为
,过点Q作
,交
于点M,连接
,分别交
于点G,H.设运动时间为
.
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712407731822592/2716811688181760/STEM/7fa4e538-dd3b-488a-aada-a97220b52553.png?resizew=443)
(1)连接
,当t为何值时,四边形
是平行四边形?
(2)设
的面积为
,求S与t之间的函数关系式;
(3)是否存在某一时刻t,使得
的面积S等于矩形面积的
?若存在,求出t的值;若不存在,说明理由.
(4)如图2,过点C作
,垂足为N,连接
,是否存在某一时刻t,使得线段
的长度有最小值?若存在,求出线段
的最小值;若不存在,说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/476dc10ad22c631ea82de5f5a5e0291f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/21037e170bdbb322558e79c40c00b454.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4bf2ed4e49655ce765ba6ffbb6c7d28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2319a01218514917e446dfc807a625ff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48ba95116dc790b935d65bf540799cea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ba0c4e4b259e4987a8c18b44f577524a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90052bd19cc64ba0aba1a97b573bf90c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5033cc18af21e0056147804f64bcbb05.png)
![](https://img.xkw.com/dksih/QBM/2021/5/2/2712407731822592/2716811688181760/STEM/7fa4e538-dd3b-488a-aada-a97220b52553.png?resizew=443)
(1)连接
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d004d2d115b477ade6af7ddb93db0df8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/422d30ae080c949ab7fd9f735e44550a.png)
(2)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e99675fa03da205c4499967c9d908412.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d39955e90413ec003f53ee0a69ef9141.png)
(3)是否存在某一时刻t,使得
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e99675fa03da205c4499967c9d908412.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ca8b26c3ad6d892590290a2304126bd.png)
(4)如图2,过点C作
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a168edba2773b3f30858f6c590b8bc7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f50b3ae183997b707d16eb4e7f6712fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f50b3ae183997b707d16eb4e7f6712fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f50b3ae183997b707d16eb4e7f6712fa.png)
2021·山东青岛·一模 查看更多[2]
更新时间:2021-05-08 20:30:26
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解答题-问答题
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【推荐1】如图,已知抛物线
:
与直线
的一个交点记为A,点A的横坐标是3.将抛物线
:
向左平移3个单位,再向下平移3个单位,得到抛物线
,直线
与
的一个交点记为B,点C是线段AB上的一个动点,过点C作x轴的垂线,垂足为D,在CD的右侧作正方形CDEF.
![](https://img.xkw.com/dksih/QBM/2020/2/10/2396213559123968/2396571964178432/STEM/7198382b135643269d931c02a1e76c38.png?resizew=141)
(1)求抛物线
的表达式及顶点坐标;
(2)当点C的横坐标为2时,直线
恰好经过正方形CDEF的顶点F,求此时n的值;
(3)在点C的运动过程中,若直线
与正方形CDEF始终没有公共点,求n的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b104090ea2ac34be58a76a4e0e95cb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/575ffdd985a9969e6de10aeac3c18bfa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d77f5191798242b7b9b88a75e17e4425.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b104090ea2ac34be58a76a4e0e95cb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/575ffdd985a9969e6de10aeac3c18bfa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7df1d9b712b639c8b6809c9f3ae03706.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d77f5191798242b7b9b88a75e17e4425.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7df1d9b712b639c8b6809c9f3ae03706.png)
![](https://img.xkw.com/dksih/QBM/2020/2/10/2396213559123968/2396571964178432/STEM/7198382b135643269d931c02a1e76c38.png?resizew=141)
(1)求抛物线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b104090ea2ac34be58a76a4e0e95cb3.png)
(2)当点C的横坐标为2时,直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd5848d7371b15965ab8990329fe04bd.png)
(3)在点C的运动过程中,若直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd5848d7371b15965ab8990329fe04bd.png)
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【推荐1】如图,在平面直角坐标系中,已知A(﹣1,0)、C(4,0),BC⊥x轴于点C,且AC=BC,抛物线y=x2+bx+c经过A、B两点.
(1)求抛物线的表达式;
(2)点E是线段AB上一动点(不与A、B重合),过点E作x轴的垂线,交抛物线于点F,当线段EF的长度最大时,求点E的坐标;
(3)在(2)的条件下,在抛物线上是否存在一点P,使△EFP是以EF为直角边的直角三角形?若存在,求出所有点P的坐标;若不存在,说明理由.
(1)求抛物线的表达式;
(2)点E是线段AB上一动点(不与A、B重合),过点E作x轴的垂线,交抛物线于点F,当线段EF的长度最大时,求点E的坐标;
(3)在(2)的条件下,在抛物线上是否存在一点P,使△EFP是以EF为直角边的直角三角形?若存在,求出所有点P的坐标;若不存在,说明理由.
![](https://img.xkw.com/dksih/QBM/2019/7/25/2254566960201728/2255646449573888/STEM/ef9a29043aef469cb08784f3b5db7c96.png?resizew=234)
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【推荐2】如图所示,在边长为1的正方形ABCD中,一直角三角尺PQR的直角顶点P在对角线AC上移动,直角边PQ经过点D,另一直角边与射线BC交于点E.
⑴试判断PE与PD的大小关系,并证明你的结论;
⑵连接PB,试证明:△PBE为等腰三角形;
⑶设AP=x,△PBE的面积为y,
①求出y关于x 函数关系式;
②当点P落在AC的何处时,△PBE的面积最大,此时最大值是多少?
⑴试判断PE与PD的大小关系,并证明你的结论;
⑵连接PB,试证明:△PBE为等腰三角形;
⑶设AP=x,△PBE的面积为y,
①求出y关于x 函数关系式;
②当点P落在AC的何处时,△PBE的面积最大,此时最大值是多少?
![](https://img.xkw.com/dksih/QBM/2011/10/17/1573267207020544/null/STEM/716dc9ff21fa4ee4a899c3ee32f2d4e8.png?resizew=190)
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【推荐3】如图,等腰直角△OEF在坐标系中,有E(0,2),F(﹣2,0),将直角△OEF绕点E逆时针旋转90°得到△ADE,且A在第一象限内,抛物线y=ax2+bx+c经过点A,E.且2a+3b+5=0.
(1)求抛物线的解析式.
(2)过ED的中点O'作O'B⊥OE于B,O'C⊥OD于C,求证:OBO'C为正方形.
(3)如果点P由E开始沿EA边以每秒2厘米的速度向点A移动,同时点Q由点A沿AD边以每秒1厘米的速度向点D移动,当点P移动到点A时,P,Q两点同时停止,且过P作GP⊥AE,交DE于点G,设移动的开始后为t秒.
①若S=PQ2(厘米),试写出S与t之间的函数关系式,并写出t的取值范围?
②当S取最小时,在抛物线上是否存在点R,使得以P,A,Q,R为顶点的四边形是平行四边形?如果存在,求出R的坐标;如果不存在,请说明理由.
(1)求抛物线的解析式.
(2)过ED的中点O'作O'B⊥OE于B,O'C⊥OD于C,求证:OBO'C为正方形.
(3)如果点P由E开始沿EA边以每秒2厘米的速度向点A移动,同时点Q由点A沿AD边以每秒1厘米的速度向点D移动,当点P移动到点A时,P,Q两点同时停止,且过P作GP⊥AE,交DE于点G,设移动的开始后为t秒.
①若S=PQ2(厘米),试写出S与t之间的函数关系式,并写出t的取值范围?
②当S取最小时,在抛物线上是否存在点R,使得以P,A,Q,R为顶点的四边形是平行四边形?如果存在,求出R的坐标;如果不存在,请说明理由.
![](https://img.xkw.com/dksih/QBM/2020/3/14/2419230864941056/2419605278515200/STEM/1cc36a60d6504ebfb05ecf3b2d25642e.png?resizew=271)
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解题方法
【推荐1】(1)问题提出:如图①,在矩形
中,
,点
为边
上一点,连接
,过点
作对角线
的垂线,垂足为
,点
为
的中点,连接
,
,
.可知
的形状为______;
![](https://img.xkw.com/dksih/QBM/2021/6/11/2740696137392128/2741573449179136/STEM/625b1e57-90f6-46ab-93d7-655e6f573a36.png?resizew=157)
(2)深入探究:如图②,将
在平面内绕点
顺时针旋转,请判断
的形状是否变化,并说明理由;(提示:延长
到
,使
;延长
到
,使
,连接
,
,
,构造全等三角形进行证明)
![](https://img.xkw.com/dksih/QBM/2021/6/11/2740696137392128/2741573449179136/STEM/13e740e47fab4c4c874c911aa5628df5.png?resizew=256)
(3)拓展延伸:如果
,
,在
旋转过程中,当点
,
,
在同一条直线上时,请直接写出
的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/010a32eb621302fe4a397f7a667d5071.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e5c62f22d7afc5627fcb86599faa8e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/907d5147cea4c9ce855074864fe54506.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274cf35acb4a1748d15c39d15a9bea7b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db650b162514681551b13eeff4fa046b.png)
![](https://img.xkw.com/dksih/QBM/2021/6/11/2740696137392128/2741573449179136/STEM/625b1e57-90f6-46ab-93d7-655e6f573a36.png?resizew=157)
(2)深入探究:如图②,将
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ff39c7aa648afd1080206c8080ff79e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/db650b162514681551b13eeff4fa046b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49b50357a6545cae8348e3059312f520.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3b1a5427d8ff23df0f3ec194756c84c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc257726f562e84ac52c8000020595f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a276f97916f8afc8eb10276ea40850a9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84f0ae0d8e74c9ca1708ce83c36c94df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bf97f9082d7f40bc680cc2c58865309.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/968b886a9f161fdcab1e08cba8ece5d0.png)
![](https://img.xkw.com/dksih/QBM/2021/6/11/2740696137392128/2741573449179136/STEM/13e740e47fab4c4c874c911aa5628df5.png?resizew=256)
(3)拓展延伸:如果
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0d5a2cd05e4476fc72271e8fdb59a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0761165f1176f3a5fe4f7b052832316d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ff39c7aa648afd1080206c8080ff79e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/907d5147cea4c9ce855074864fe54506.png)
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【推荐2】如图1,矩形OABC的顶点A、C分别在x、y轴的正半轴上,点B在反比例函数y=
(k>0)的第一象限内的图像上,OA=6,OC=4,动点P在y轴的右侧,且满足S△PCO=
S矩形OABC.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/8/b6486a60-23dc-4676-aeb3-6f9f7f3b1396.png?resizew=438)
(1)若点P在这个反比例函数的图像上,求点P的坐标;
(2)若点Q是平面内一点,使得以B、C、P、Q为顶点的四边形是菱形,请你直接写出 满足条件的所有点Q的坐标.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9abb3a62e46296c417261156b51ec6b4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f16d09692f7b0fb5633964437202d21d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/8/b6486a60-23dc-4676-aeb3-6f9f7f3b1396.png?resizew=438)
(1)若点P在这个反比例函数的图像上,求点P的坐标;
(2)若点Q是平面内一点,使得以B、C、P、Q为顶点的四边形是菱形,请你
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【推荐3】【教材呈现】下图是华师版八年级下册数学教材第121页的部分内容.
,将矩形纸片沿过点
的直线折叠,使点
落在边
上,点
的对应点为
,折痕为
,点
在
上.求证:四边形
是正方形.
【规律探索】(2)由【问题解决】可知,图①中的
为等腰三角形.现将图①中的点
沿
向右平移至点
处(点
在点
的左侧),如图②,折痕为
,点
在
上,点
在
上,那么
还是等腰三角形吗?请说明理由.
【结论应用】(3)在图②中,当
时,将矩形纸片继续折叠如图③,使点
与点
重合,折痕为
,点
在
上.要使四边形
为菱形,则
___________.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d83c15e14023ca74a365b685f363a87c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0054610b07c11f3cb88aa87b58c2df11.png)
【规律探索】(2)由【问题解决】可知,图①中的
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/791c9a8ecce70f679855ee110d446f8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c314398e26ffc7164b82946eeb4273.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fb26d84907c923278ac4626a9d58947.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9e52a8f07834cbbbe4224962672fbbb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e24d57917c6e6ab5b6e5421d308cc7ce.png)
【结论应用】(3)在图②中,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc5ce139702cc0eaf15022712510c394.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/55bb0405afa96ebf94c5b03fd52763dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/895dc3dc3a6606ff487a4c4863e18509.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ee1c8afa520493001a697f9842cd497.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c96e57c0595d832191594d11a1a0f15f.png)
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解答题-证明题
|
较难
(0.4)
解题方法
【推荐1】如图,在矩形
中,点E为
的中点,连接
,过点D作
于点F,过点C作
于点N,延长
交
于点M.
(1)求证:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/176822d1db2fd6726ec2e8ab733dfa8e.png)
(2)连接CF,并延长CF交AB于G
①若
,求
的长度;
②探究当
为何值时,点G恰好为AB的中点.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8689d619c2508c9000531fc1b8f1f21c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1ac30ad6393440bfa0a4471c132ae2b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/167d31eb8432b5c0364316e5048c23dd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/176822d1db2fd6726ec2e8ab733dfa8e.png)
(2)连接CF,并延长CF交AB于G
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4cae70b8a9d2d2e96dea62c00ced04b9.png)
②探究当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0636e0c3ae734c1ac05ef4d53b1f2a92.png)
![](https://img.xkw.com/dksih/QBM/2020/5/18/2465591764254720/2466245797093376/STEM/7562d571dd014d75b04cb5f082420736.png?resizew=194)
您最近一年使用:0次
解答题-证明题
|
较难
(0.4)
【推荐2】(1)问题发现
如图1,四边形ABCD为矩形,AB=a,BC=b,点P在矩形ABCD的对角线AC上,Rt△PEF的两条直角边PE,PF分别交BC,DC于点M,N,当PM⊥BC,PN⊥CD时,
= (用含a,b的代数式表示).
(2)拓展探究
在(1)中,固定点P,使△PEF绕点P旋转,如图2,
的大小有无变化?请仅就图2的情形给出证明.
(3)问题解决
如图3,四边形ABCD为正方形,AB=BC=a,点P在对角线AC上,M,N分别在BC,CD上,PM⊥PN,当AP=nPC时,(n是正实数),直接写出四边形PMCN的面积是 (用含n,a的代数式表示)
如图1,四边形ABCD为矩形,AB=a,BC=b,点P在矩形ABCD的对角线AC上,Rt△PEF的两条直角边PE,PF分别交BC,DC于点M,N,当PM⊥BC,PN⊥CD时,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc8d08ed44ae7ed558a9d7d4c21c2e3e.png)
(2)拓展探究
在(1)中,固定点P,使△PEF绕点P旋转,如图2,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fc8d08ed44ae7ed558a9d7d4c21c2e3e.png)
(3)问题解决
如图3,四边形ABCD为正方形,AB=BC=a,点P在对角线AC上,M,N分别在BC,CD上,PM⊥PN,当AP=nPC时,(n是正实数),直接写出四边形PMCN的面积是 (用含n,a的代数式表示)
![](https://img.xkw.com/dksih/QBM/2018/5/16/1946560882065408/1947457873657856/STEM/fbf180d6d4a14d00b3b6cb075207108e.png?resizew=315)
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