如图,已知二面角
为
,
与平面
成30°角.若△ACD的面积为S,那么,
为何值时,△BCD的面积有最大值?最大值是多少?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/40376a34076874359d37a08a5d2367a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f53d9200c2d733c4ffc1cbe3b1dafb8d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/9/014f483e-2ccb-4670-8900-59231bbb3b1d.png?resizew=187)
2006高三·山东·竞赛 查看更多[1]
(已下线)2006年全国高中数学联赛山东赛区预赛试题
更新时间:2018-12-22 09:42:36
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相似题推荐
解答题-证明题
|
适中
(0.65)
【推荐1】如图,在
中,
,在边
上分别取点
,使
设
与
交于点
,过
的直线与
分别交于点
,且
求证:![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9de193f7c87cc62fed59f9953e4403da.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7732583380d075d7ca469f9722130834.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0d54431bbb28ebd98db5c1dc6083a75.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/49f31a1284206d3a2fdea63f2a6983b1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95227bd2061247870d20b1309339d14e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cb6ede9761b5b90f8dc137708e1ee90f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0cb6fd2fa53b92a03d21f208b74e3857.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a18722354086c42e62334983fc50eb6a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/208bc3c512decc06c872dc0d2083f978.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/04477473bcaa0a53170c7e9088e77b33.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4414bd2cbe4465677640a3dcee935dcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9de193f7c87cc62fed59f9953e4403da.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/5/e30f0558-6c86-4fdf-a46e-40da6cd53f98.png?resizew=145)
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解答题-问答题
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适中
(0.65)
【推荐2】凸四边形
的对角线交点为
.证明:
是圆外切四边形的充分必要条件是
、
、
、
的内切圆半径
、
、
、
满足关系式
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/866b81a8384cce4f24867baca2e6820c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a7ffcd1925a2b1259221c6a476152f7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a9a6eeeebf3cff569578d7366b755aa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/314c024e7e1467e8c1e0ccdb96007462.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2858005b9ae89ae080d83dcc13cf8e81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2b3e95410f3b4fcb0cba425b521d1f67.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f2cb48c0a69b8c420c0b64b2bfa1ef7.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/780f3b16573bc64d001506f4ede38bbd.png)
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解答题-问答题
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适中
(0.65)
【推荐1】如图已知四面体
中,
.
(1)指出与面
垂直的侧面,并加以证明;
(2)若
,二面角
的平面角为
,求
的表达式和
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b40114b048a4736d62835c4896e1181c.png)
(1)指出与面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0d24e6881eacbe93488d5c4e6514c7c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c2898853a3396f0878af9eac934416d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c7561d130c27f5a972d36887248028ff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e170f206fdbbd834aad7580c727e2cc6.png)
![](https://img.xkw.com/dksih/QBM/2018/12/14/2096456048517120/2097363383246848/STEM/ee82df4c655a4a82bd98af231794f5fd.png?resizew=224)
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解答题-问答题
|
适中
(0.65)
【推荐2】已知三棱锥P-ABC的平面展开图中,四边形ABCD为边长等于
的正方形,△ABE和△BCF均为正三角形,在三棱锥P-ABC中:
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/28/4ba5efea-4e0a-45a8-854b-fb8c44425128.png?resizew=345)
(1)证明:平面PAC⊥平面ABC;
(2)若点M为棱PA上一点且
,求二面角P-BC-M的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/95bacae35b6e16a0a33c2bdc6bc07df7.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/28/4ba5efea-4e0a-45a8-854b-fb8c44425128.png?resizew=345)
(1)证明:平面PAC⊥平面ABC;
(2)若点M为棱PA上一点且
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dcd9780b6f5b877fc09ddd7f0b001dc8.png)
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解答题-问答题
|
适中
(0.65)
【推荐1】两两外切且半径分别为1、2、3的三个实心木球,球
、球
、球
夹在“
”字型木架之间(每个球与
字型木架两个面相切),求
字型木架两个面的夹角的度数.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23f919bd3dde10dbbc076f7ec5149699.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c4f6f74444b2b7947fc6e35c8d62322.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6dacb04fa29178c0af4353e4369a7e69.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be54e84508decfcce6d2fcbe6c8c1a92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be54e84508decfcce6d2fcbe6c8c1a92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be54e84508decfcce6d2fcbe6c8c1a92.png)
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解答题-问答题
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适中
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解题方法
【推荐2】已知正方体
的棱长为a.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/24/f86306c9-4a1b-447a-bbb7-0e291f9546c3.png?resizew=159)
(1)求点
到平面
的距离;
(2)求平面
与平面
所成的二面角(结果用反三角函数值表示).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/24/f86306c9-4a1b-447a-bbb7-0e291f9546c3.png?resizew=159)
(1)求点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1241216f3c1cb5e73043dd1037f556d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fae7f4612c548b1f72a964ddb291cd2e.png)
(2)求平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82b724168afaee2ecddf97257180be18.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fae7f4612c548b1f72a964ddb291cd2e.png)
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