在正三棱锥
中,侧棱
,底面边长
,设点
在平面
上的正投影为
.连接
并延长交
于点
.
![](https://img.xkw.com/dksih/QBM/2020/9/1/2540573234184192/2543474605858816/STEM/78f2d359-4f6d-4e3b-a0a4-8d00966fb4a0.png?resizew=213)
(1)求证:
为
的中点;
(2)若过点
且平行于底面
的平面与
、
、
分别交于点
、
、
,求三棱锥
的体积.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41e5db1d2fd912f77923e4c120a7dc19.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f3c9afe5837b9e42137d69bb1658ae43.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/305a88d4e0249bd16d48eda01331d2d4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5000fea066102e62cf2128ccbbd2b3e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/34c157ff302a881c17514534903c575f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://img.xkw.com/dksih/QBM/2020/9/1/2540573234184192/2543474605858816/STEM/78f2d359-4f6d-4e3b-a0a4-8d00966fb4a0.png?resizew=213)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
(2)若过点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a6e2867f32d3f1c3cd36cd3a11a8580.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d4db9b82b67efe45a02fca32bfcf5dc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c2bc5e50b8dfa02601c70822252854a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e527171b2a771265e3d56b64edf16054.png)
更新时间:2020-09-05 22:55:14
|
相似题推荐
解答题-证明题
|
适中
(0.65)
解题方法
【推荐1】如图(1),在边长为
的正三角形ABC中,D,E分别为AB,AC中点,将
沿DE折起,使二面角
为直二面角,如图(2),连接AB,AC.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/3/7d9729bf-a30a-4ed1-b5b5-bf0c31c32269.png?resizew=345)
(1)求四棱锥
的体积;
(2)在图(2)中,过点E作平面EFG与平面ABD平行,分别交BC,AC于F,G.求证:
平面ABC.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b8860d9787671b53b1ab68b3d526f5ca.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a25c28359f8d8da9eaf4672a6cf8ae4f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/370148e9147aa25c60a07ab4ad46e83d.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/5/3/7d9729bf-a30a-4ed1-b5b5-bf0c31c32269.png?resizew=345)
(1)求四棱锥
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a8e7cedc39297d66dbb177f2a1f6bee2.png)
(2)在图(2)中,过点E作平面EFG与平面ABD平行,分别交BC,AC于F,G.求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1d0df73a49d4348a5c1e3aaa149cc8a.png)
您最近一年使用:0次
【推荐2】据说伟大的阿基米德逝世后,敌军将领马塞拉斯给他建了一块墓碑,在墓碑上刻了一个如图所示的图案,图案中球的直径、圆柱底面的直径和圆柱的高相等,圆锥的顶点为圆柱上底面的圆心,圆锥的底面是圆柱的下底面.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/14/b387f30d-d7c1-422b-9d35-f92b8bd46e2b.png?resizew=98)
(1)试计算出图案中圆柱与球的体积比:
(2)假设球半径
,试计算出图案中圆锥的体积和表面积.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/14/b387f30d-d7c1-422b-9d35-f92b8bd46e2b.png?resizew=98)
(1)试计算出图案中圆柱与球的体积比:
(2)假设球半径
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8176754726d2194c890e80df1a1f1c3a.png)
您最近一年使用:0次
解答题-证明题
|
适中
(0.65)
【推荐1】如图,四棱锥
中,
,
,
,
,
为线段
上一点,且
.
![](https://img.xkw.com/dksih/QBM/2020/8/26/2536413847330816/2542613455577088/STEM/58f38968-f76b-4830-839e-0d0aabdfc3bb.png)
(1)求证:
;
(2)求直线
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10df84d553a8826a7ce9bff4bf0d95b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1134c8e3440abb6cd385af2c169037fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/746f70c9993f04a5037c53daf3d1af00.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/119d910e751ec4bd1e43e17e5404d6cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2be49c37e30a3ced0364c3e74d8c687.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/aa4eebde0291ae62d02a498b56358ece.png)
![](https://img.xkw.com/dksih/QBM/2020/8/26/2536413847330816/2542613455577088/STEM/58f38968-f76b-4830-839e-0d0aabdfc3bb.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b44f4120c94cb7176dc31fcac387b32e.png)
(2)求直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48f3c9abbd78e9a6840ee5f30381daac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfe67036b4671b5d2a5c55b48c4d3bb9.png)
您最近一年使用:0次
解答题-问答题
|
适中
(0.65)
解题方法
【推荐2】如图,在三棱柱
中,点
在底面
内的射影恰好是点C.
![](https://img.xkw.com/dksih/QBM/2022/3/14/2936167502979072/2938706614804480/STEM/3d2c644740df449bb8321c61f5143d1e.png?resizew=189)
(1)若点D是
的中点,且
,证明:
.
(2)已知
,过
作底面
的垂线(指出垂足),写出作法,并求
的周长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97c01fdc7bc471af0b264a04aef0823e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://img.xkw.com/dksih/QBM/2022/3/14/2936167502979072/2938706614804480/STEM/3d2c644740df449bb8321c61f5143d1e.png?resizew=189)
(1)若点D是
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c48119b3932497634478f656c752ec4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ffeea0a84cdd67bd8bed95bc0f8ae364.png)
(2)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a91b1e0822a372acb8098045ab46e031.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1241216f3c1cb5e73043dd1037f556d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/98474425eb86a28f2b01cec95643ae7d.png)
您最近一年使用:0次