解题方法
1 . “用一个不垂直于圆锥的轴的平面截圆锥,当圆锥的轴与截面所成的角不同时,可以得到不同的截口曲线”.利用这个原理,小明在家里用两个射灯(射出的光锥视为圆锥)在墙上投影出两个相同的椭圆(图1),光锥的一条母线恰好与墙面垂直.图2是一个射灯投影的直观图,圆锥
的轴截面
是等边三角形,椭圆
所在平面为
,则椭圆
的离心率为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef49a3ca580a144cc65a609c167facc1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/745e0525a41fe2e2a7739c75a942290b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3f4b27f503ce08bc7851006a98f9ce32.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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2 . 在近期学校组织的论文展示大赛中,同学们发现数学在音乐欣赏中起着重要的作用
纯音的数学模型是三角函数
如音叉发出的纯音振动可表示为
,其中
表示时间,
表示纯音振动时音叉的位移
我们听到的每个音是由纯音合成的,若某合音的数学模型为函数
,且声音的质感与
的参数有关,比如:音调与声波的振动频率有关,频率低的声音低沉,频率高的声音尖利.
(1)当
时,函数
的对称中心坐标为______ ;
(2)当
时,合音
的音调比纯音![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c7a72ab550b89f838b0f71a24c20f4bb.png)
______ (填写“高”或“低”).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c90282d4a37c9a20620d4bbb0c263cae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c90282d4a37c9a20620d4bbb0c263cae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42f0670a61f0274e80b47844cea59ac1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c90282d4a37c9a20620d4bbb0c263cae.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8fe5c8a68ce20e3b6551d9fb67ea85fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/51c530f4b7491b95acb8ce3eef9aa09d.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c87b351f16728b0023fd63678f8103c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d0b87383da5b68e452263e205594f334.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c7a72ab550b89f838b0f71a24c20f4bb.png)
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3 . 图象识别是人工智能领域的一个重要研究方向.某中学人.工智能兴趣小组研发了一套根据人脸照片识别性别的程序.在对该程序的一轮测试中,小组同学输入了200张不同的人脸照片作为测试样本,获得数据如下表(单位:张):
假设用频率估计概率,且该程序对每张照片的识别都是独立的.
(1)从这200张照片中随机抽取一张,已知这张照片的识别结果为女性,求识别正确的概率;
(2)在新一轮测试中,小组同学对3张不同的男性人脸照片依次测试,每张照片至多测一次,当首次出现识别正确或3张照片全部测试完毕,则停止测试.设
表示测试的次数,估计
的分布列和数学期望
;
(3)为处理无法识别的照片,该小组同学提出上述程序修改的三个方案:
方案一:将无法识别的照片全部判定为女性;
方案二:将无法识别的照片全部判定为男性;
方案三:将无法识别的照片随机判定为男性或女性(即判定为男性的概率为50%,判定为女性的概率为
.
现从若干张不同的人脸照片(其中男性、女性照片的数量之比为
)中随机抽取一张,分别用方案一、方案二、方案三进行识别,其识别正确的概率估计值分别记为
.试比较
的大小.(结论不要求证明)
识别结果 真实性别 | 男 | 女 | 无法识别 |
男 | 90 | 20 | 10 |
女 | 10 | 60 | 10 |
(1)从这200张照片中随机抽取一张,已知这张照片的识别结果为女性,求识别正确的概率;
(2)在新一轮测试中,小组同学对3张不同的男性人脸照片依次测试,每张照片至多测一次,当首次出现识别正确或3张照片全部测试完毕,则停止测试.设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f022950e0faa45b617d497b01b5292b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/809bea8ceacc497b23a74f4ab3307327.png)
(3)为处理无法识别的照片,该小组同学提出上述程序修改的三个方案:
方案一:将无法识别的照片全部判定为女性;
方案二:将无法识别的照片全部判定为男性;
方案三:将无法识别的照片随机判定为男性或女性(即判定为男性的概率为50%,判定为女性的概率为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fdb3299f9bf45bdbfd54b53b7ccc7391.png)
现从若干张不同的人脸照片(其中男性、女性照片的数量之比为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf1c295fd10f4dcc21955ce39560b5c6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9bf0198e73b44944ce7a45411899f49.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9bf0198e73b44944ce7a45411899f49.png)
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解题方法
4 . 如图是两个齿轮传动的示意图,已知上、下两个齿轮的半径分别为1和2,两齿轮中心
,
在同一竖直线上,且
,标记初始位置
点为下齿轮的最右端,
点为上齿轮的最下端,以下齿轮中心
为坐标原点,如图建立平面直角坐标系
,已知下齿轮以每秒1弧度的速度逆时针旋转,并同时带动上齿轮转动,转动过程中
,
两点的纵坐标分别为
,
、转动时间为
秒(
).
时,求点
绕
转动的弧度数;
(2)分别写出
,
关于转动时间
的函数表达式,并求当
满足什么条件时,
;
(3)求
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c4f6f74444b2b7947fc6e35c8d62322.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a31a569bdc08b10b6df2173b300eab1d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ee31829d0d4d5f779a957d7df8058ab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54015ff5b49e3283901da1291b6b921d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46f6872ffb1934339c53c2c2282d5889.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c81b29ac8a01886b25dcef55c5f6877.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a2a51944c720568f35d443589dfc1aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c4f6f74444b2b7947fc6e35c8d62322.png)
(2)分别写出
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54015ff5b49e3283901da1291b6b921d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46f6872ffb1934339c53c2c2282d5889.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5210da913651389fbe68c4dcba271d6.png)
(3)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a7d77da1072b8daf89ae9f26d2ca351.png)
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解题方法
5 . 已知椭圆
的焦点在
轴上,中心在坐标原点.以
的一个顶点和两个焦点为顶点的三角形是等边三角形,且其周长为
.
(1)求栯圆
的方程;
(2)设过点
的直线
(不与坐标轴垂直)与椭圆
交于不同的两点
,与直线
交于点
.点
在
轴上,
为坐标平面内的一点,四边形
是菱形.求证:直线
过定点.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8ec978eb43bc4f9e7df83b0d0195dcda.png)
(1)求栯圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
(2)设过点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99296bab1b42898e7ca336a822510258.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f85fca60a11e1af2bf50138d0e3fe62.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/098a3e7d1f1890863b7483a98b618119.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/592830c3456745cee7d6d1cdc4f5631f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0629ce42392a7fe9be21d25c39c3e64.png)
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6 . 设数列
的各项均为非零的整数,其前
项和为
.若
为正偶数,均有
,且
,则
的最小值为( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a94774a88d80d7c78f103c095f68a152.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/44bf235c15687a5a6b68b7c98ac66013.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdd3a25ac2cde3d2c884028f750cfff8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f3cf6f2bbe20a404fea41a4d2b1c4c7.png)
A.0 | B.22 | C.26 | D.31 |
您最近一年使用:0次
7 . 设正整数
,
,
,这里
. 若
,且
,则称
具有性质
.
(1)当
时,若
具有性质
,且
,
,
,令
,写出
的所有可能值;
(2)若
具有性质
:
①求证:
;
②求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0704f453b2de48d36911f7db496bbf82.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/25c53838698bdce4bdfcddb756b60f52.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b30f859c1ac6d40ecd3660efd6639b25.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/12b0e3b00fe47801afb53ec56706c21a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cef463abd621083c32b0a43fd95373ef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/14fb04e3704e9e0bc2a610815f29f09f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/252bab154aa5bdc9b4bce4c0d43aaf73.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be604061cf1591f7069472269d4c9719.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6fa157b4f65f3a9aa1f7f82de02e99e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b065334d8f60c49f4bd3d9f1373fe4cd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c9b6e51986fe5d7a7265e0e93adcb4d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ced4e381e8c3336848b8c436dbc584f3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6831ec7292bd1e0fc7e21efb4d82357b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/252bab154aa5bdc9b4bce4c0d43aaf73.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
①求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e9171aebb446d064b05a8c9513b77713.png)
②求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dbb2d69dacbf149f01a3e98b33f8e01.png)
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名校
8 . 在平面直角坐标系中,
为原点,
,
,
,
,
,
为线段
上一点,且
.
(1)求
,
的值;
(2)当
时,求
;
(3)求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f54dd475ff1321041c80738b201c3b6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c53cfa785f3d78e95a3b170180fd4b4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f384287369cd6c433fea28ef0cae8f1c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/39346db456e8935d6d95a14b1d50ccde.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/094ff53768a384f25105a6eee42d4920.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c8ffefb797217233ec7257fc8a93da0.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/220fbc3a2a1db04a91719fc8110e0e80.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/46337843811aa7723d42cfd9d815bff1.png)
(3)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab7aaa871ceb78e5b80b531a7cf4f1c9.png)
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9 . 设
为正整数,集合
对于
,设集合
.
(1)若
,写出集合
;
(2)若
,且
满足
令
,求证:
;
(3)若
,且
,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb39983c5c3fc32d3f0a2c98f04cdb3b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ee7981aba05ee1d4945062913c8db8c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08897069d8b3e4c9f42a768d7ae2d416.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/40deecdcc73cfee7fe7624a813af16ec.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aeff5c5f7214a5f9b920af89af5b3802.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ee7981aba05ee1d4945062913c8db8c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c5c31ea128ff2a390979894f53486f6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/695e27822adf2901dd6f48a1a29e68d5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/764928f3bec8c40cbff944c0b36ffb57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/18bf5b3e05fdd0bdb9597f5b9d2386cf.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2ee7981aba05ee1d4945062913c8db8c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f53037f80f8cf5faf2f861a3859c3166.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8aa4b0e70b5c191c6391263d905c52b0.png)
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10 . 假设某飞行器在空中高速飞行时所受的阻力
满足公式
,其中
是空气密度,
是该飞行器的迎风面积,
是该飞行器相对于空气的速度,
是空气阻力系数(其大小取决于多种其他因素),反映该飞行器克服阻力做功快慢程度的物理量为功率
. 当
不变,
比原来提高
时,下列说法正确的是( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca4ff0af96ea467337cb30c4c765b5f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ed280544911aa91a07b26a2ed09e39c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/171102a883b22fe6ca578efc8926f5b8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc13a607ac0c7f76d252d7cb1bb040fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a344acb1ed9c08dc5f355ff74d01bafa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ae5e401a716bc52bed83b53c447eacb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bc13a607ac0c7f76d252d7cb1bb040fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/522fdf99d6e1ae6757428932e5d319db.png)
A.若![]() ![]() ![]() |
B.若![]() ![]() ![]() |
C.为使![]() ![]() ![]() |
D.为使![]() ![]() ![]() |
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