如图,四棱锥
中,侧面
底面
,
,
,
,
.
(1)证明:直线
平面
;
(2)若四棱锥
的体积为8,求三棱锥
的内切球的表面积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/93edc7bb513f40a89173121c8570cd65.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/62974d34de3a12418d6b700420afd1b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d78aafccd397e9c88a567abf4993d40f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7af36689a2d2a5f999b3b5859a3c9faf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ab7035a9fec5e29efa502355a1063ee.png)
(1)证明:直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/858d8ee9f0898409afc55f6fa5d95be7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/852aabd89edffc1b94344ff3f1f31ccd.png)
(2)若四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c482ee1668a59ca21f3ae8b6bad58eae.png)
![](https://img.xkw.com/dksih/QBM/2018/7/10/1985665897897984/1987379012755456/STEM/e2bebd4e8377487c963e996a2bd3205c.png?resizew=125)
更新时间:2018-07-13 06:35:51
|
相似题推荐
解答题-证明题
|
适中
(0.65)
名校
【推荐1】如图,四棱锥
中,四边形
为矩形,
,
,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/74475663-c355-455d-bbf0-c3f374a53c06.png?resizew=183)
(1)求证:
平面
;
(2)求四棱锥
外接球的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/080ca48cd27d4bf9d9ef084b558fc17a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da426f62147ca7fb8d3314ca9dffbeb2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9971233dc3e8ef828046fbb94101b9d0.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/4/74475663-c355-455d-bbf0-c3f374a53c06.png?resizew=183)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6deecf9ccb7b7879455050633219e09.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4d923a338dd2d2e29336b42574d38448.png)
(2)求四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/faeb97acf19bd3b2c6c77c2814df4d2f.png)
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【推荐2】在棱长为1的正方体内有两个球相外切且又分别与正方体内切.
(1)求两球半径之和;
(2)球的半径为多少时,两球体积之和最小.
(1)求两球半径之和;
(2)球的半径为多少时,两球体积之和最小.
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解答题-证明题
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解题方法
【推荐1】如图,在三棱柱
中,各个侧面均是边长为
的正方形,
为线段
的中点
![](https://img.xkw.com/dksih/QBM/2019/1/4/2111489997422592/2113866393346048/STEM/c5cd7d53a8664549a721fd6106949777.png?resizew=148)
(Ⅰ)求证:
⊥平面
;
(Ⅱ)求证:直线
∥平面
;
(Ⅲ)设
为线段
上任意一点,在
内的平面区域(包括边界)是否存在点
,使
,并说明理由
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://img.xkw.com/dksih/QBM/2019/1/4/2111489997422592/2113866393346048/STEM/e24a6d72d7de44fb885bc913a03f89c8.png?resizew=13)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://img.xkw.com/dksih/QBM/2019/1/4/2111489997422592/2113866393346048/STEM/c5cd7d53a8664549a721fd6106949777.png?resizew=148)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d9a8181f7a7fe7f3fac872ce9534f15.png)
(Ⅱ)求证:直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b470c4e195cf7a07b7a331ce4b436e03.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a935b7d21a103a264b6e96ecf82dbe4a.png)
(Ⅲ)设
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d8772aa893a9c1d40f714cb25701701.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d021334737f555d75a65177f7ebebc81.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fd5260b9927d0ad83b03c1e24c586e98.png)
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【推荐2】如图,在直四棱柱
中,底面
是菱形,
,
,
,
是
的中点.
(1)求证:
平面
;
(2)求直线
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fcd0ced286a0fbc7e4862f8147264277.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e55a2310cbba5e050488cd9296eb195d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8bbaccd578a43b2397c8bdd50592fa07.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22adbc0da438220f9cace11b629d799b.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/9/19/e50033c1-3861-4cf9-ae2c-de050848314e.png?resizew=123)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45c4868519925e6297a716def14d5662.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/923189afc198d153c79059a827f63c87.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/923189afc198d153c79059a827f63c87.png)
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(0.65)
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【推荐3】如图所示,正方形
与梯形
所在的平面互相垂直,
,
,
,
.
时,求证:
平面
;
(2)若平面
与平面
所成锐角二面角的余弦值为
时,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ecc1cb55a57dde481f8dd07ab150676.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cdb2dd10731b99c0f4f89ee957f8a239.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ecc1cb55a57dde481f8dd07ab150676.png)
(2)若平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bc46688d8723cf2003fc25890265200.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20af148464904e21f4374cc8fb886fba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aae9be8eff03ecce9033c3841b63cf7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
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