如图,在Rt△ABC中,∠BAC=90°,AB=AC=16cm,AD为BC边上的高.动点P从点A出发,沿A→D方向以
cm/s的速度向点D运动.设△ABP的面积为S1,长方形 PDFE的面积为S2,运动时间为t秒(0<t<8),则t=( )秒时,S1=2S2.
![](https://img.xkw.com/dksih/QBM/2022/3/25/2943954212257792/3060488332263424/STEM/54c60486d5434da2851b08624b26b86b.png?resizew=198)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
![](https://img.xkw.com/dksih/QBM/2022/3/25/2943954212257792/3060488332263424/STEM/54c60486d5434da2851b08624b26b86b.png?resizew=198)
A.5 | B.6 | C.7 | D.8 |
21-22八年级下·浙江舟山·阶段练习 查看更多[3]
浙江省舟山市普陀区沈家门第一初级中学2021-2022学年八年级下学期3月月考数学试题(已下线)第12讲 用相似三角形解决问题-【帮课堂】2022-2023学年九年级数学下册同步精品讲义(苏科版)浙江省杭州市余杭区中泰中学等2校2022-2023学年八年级下学期3月月考数学试题
更新时间:2022-09-06 10:02:21
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【推荐1】如图①,在矩形
中,
,对角线
、
相交于点
,动点
由点
出发,沿
运动,设点
的运动路程为
,
的面积为
,
与
的函数关系图像如图②所示,则
边的长为( )
![](https://img.xkw.com/dksih/QBM/2021/7/9/2760356115939328/2818498718195712/STEM/08509d3a-efdb-4982-ac3e-58fe48b29333.png?resizew=235)
![](https://img.xkw.com/dksih/QBM/2021/7/9/2760356115939328/2818498718195712/STEM/3e1ec01a-1269-48b0-bf4d-050b0413b558.png?resizew=229)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b9199a3de404cb13ae7710f73db5c8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bfd66776565f049eb453c14fcaf79234.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e2b4dcc093218443f71a046b6df94bbe.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
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![](https://img.xkw.com/dksih/QBM/2021/7/9/2760356115939328/2818498718195712/STEM/08509d3a-efdb-4982-ac3e-58fe48b29333.png?resizew=235)
![](https://img.xkw.com/dksih/QBM/2021/7/9/2760356115939328/2818498718195712/STEM/3e1ec01a-1269-48b0-bf4d-050b0413b558.png?resizew=229)
A.3 | B.4 | C.5 | D.6 |
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【推荐2】如图,在
中,
,
,
,点P从点A开始沿AC 边向点C以
的速度匀速移动,同时另一点Q由C点开始以
的速度沿着射线CB匀速移动,当
的面积等于
运动时间为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/987517758fad59f6f695761deb2a5ebd.png)
![](https://img.xkw.com/dksih/QBM/2018/12/15/2097230987714560/2099323691638784/STEM/4ba67d5677e7432a8e7f8555d667eb19.png?resizew=165)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e428e7a09732be85c1224e9c8f6a71c5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b7fcf7c793d3e26f79b5909fb82dcb77.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/06788928d1f851a66b89838e4da2d294.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e040fc34352770f1b024b38bd1e9b84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c06a42eee5f3ac30899b7096520c4a65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f34b7b29b3fdfdf47f943a396de462db.png)
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![](https://img.xkw.com/dksih/QBM/2018/12/15/2097230987714560/2099323691638784/STEM/4ba67d5677e7432a8e7f8555d667eb19.png?resizew=165)
A.5秒 | B.20秒 | C.5秒或20秒 | D.不确定 |
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【推荐1】我国古代数学家刘徽发展了“重差术”,用于测量不可到达的物体的高度,比如,通过下列步骤可测量山的高度PQ(如图):
(1)测量者在水平线上的A处竖立一根竹竿,沿射线QA方向走到M处,测得山顶P、竹竿顶端B及M在一条直线上;
(2)将该竹竿竖立在射线QA上的C处,沿原方向继续走到N处,测得山顶P、竹竿顶端D及N在一条直线上;
(3)设竹竿与AM、CN的长分别为
、a1、a2,可得公式:PQ=
+
.则上述公式中,d表示的是( )
![](https://img.xkw.com/dksih/QBM/2018/12/14/2096819152945152/2099881793650688/STEM/f9d74fdd6f2144c981aa6c4273ccf067.png?resizew=198)
(1)测量者在水平线上的A处竖立一根竹竿,沿射线QA方向走到M处,测得山顶P、竹竿顶端B及M在一条直线上;
(2)将该竹竿竖立在射线QA上的C处,沿原方向继续走到N处,测得山顶P、竹竿顶端D及N在一条直线上;
(3)设竹竿与AM、CN的长分别为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f241f581956c0f5bf78648fce2d46e9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://img.xkw.com/dksih/QBM/2018/12/14/2096819152945152/2099881793650688/STEM/f9d74fdd6f2144c981aa6c4273ccf067.png?resizew=198)
A.QA的长 | B.AC的长 | C.MN的长 | D.QC的长 |
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【推荐2】如图,在Rt△ABC中,∠ACB=90°,∠A=60°,AC=2,D是AB边上一个动点(不与点A、B重合),E是BC边上一点,且∠CDE=30°.设AD=x,BE=y,则下列图象中,能表示y与x的函数关系的图象大致是( )
![](https://img.xkw.com/dksih/QBM/2019/6/7/2220386506121216/2224609893220352/STEM/3eb53a02d6804e2cbbb87992f7638f8c.png?resizew=173)
![](https://img.xkw.com/dksih/QBM/2019/6/7/2220386506121216/2224609893220352/STEM/3eb53a02d6804e2cbbb87992f7638f8c.png?resizew=173)
A.![]() | B.![]() | C.![]() | D.![]() |
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