在正三棱柱
中,
,
是
的中点,
是
的中点.
(1)求证:
平面
;
(2)求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1baa3d0db9ad31d33c2883a6efed1dc7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e26d9636ad77369535852c6e4493446a.png)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a2b5cfae407016cad45bbdefea05833.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
(2)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e39b13d187b25461d85a3b8d10c7b678.png)
更新时间:2022-09-20 13:37:38
|
相似题推荐
解答题-问答题
|
适中
(0.65)
解题方法
【推荐1】下图是一个正三棱柱(以
为底面)被一平面所截得到的几何体,截面为
.已知
,
,
,
.
![](https://img.xkw.com/dksih/QBM/2016/1/22/1572463379816448/1572463385960448/STEM/b721e6e1d1374f23af0df68a1c9eba5c.png)
(1)设点
是
的中点,证明:
平面
;
(2)求
与平面
所成的角的正弦值;
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99b16cff607cdc2d69afc70dc778acbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bef5239ddbb0972700ce01daf9ee7cf.png)
![](https://img.xkw.com/dksih/QBM/2016/1/22/1572463379816448/1572463385960448/STEM/eeea238797af4d30af00fbd8270f70d7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e55a2310cbba5e050488cd9296eb195d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41fd676c41d2d644928f014b0fea4689.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c122ca7141c43c15c783968f5f0dbc19.png)
![](https://img.xkw.com/dksih/QBM/2016/1/22/1572463379816448/1572463385960448/STEM/b721e6e1d1374f23af0df68a1c9eba5c.png)
(1)设点
![](https://img.xkw.com/dksih/QBM/2016/1/22/1572463379816448/1572463385960448/STEM/6a7de21ee6424115a15666bc7d053c59.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://img.xkw.com/dksih/QBM/2016/1/22/1572463379816448/1572463385960448/STEM/88b45c8aad22499b9e1d892eb8916d6b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99b16cff607cdc2d69afc70dc778acbb.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://img.xkw.com/dksih/QBM/2016/1/22/1572463379816448/1572463385960448/STEM/d0f4ba95fbef46a7b1236dc8a97b313b.png)
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解答题-问答题
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适中
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【推荐2】如图,棱长为2的正方体
中,P,Q分别是棱
的中点.
与直线
交于R点,求
的值;
(2)在线段
上是否存在点M,使得
面
,若存在,请求出M点位置并证明;若不存在,请说明理由.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/782ee40013d63fa0c5802990608ff45a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81cd729469b9aa6655beb1c6c6198476.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6fae3a8b395f14718d3e5980e6451be1.png)
(2)在线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f369bec2d5682bf6b8b317a08aff546.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81cd729469b9aa6655beb1c6c6198476.png)
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【推荐3】如图,在多面体
中,
平面ABC,且
,
为AB的中点.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/21/731186a4-9a8d-4d8b-b384-b7bd40488bcb.png?resizew=149)
(Ⅰ)求证:
平面
;
(Ⅱ)若
,求二面角
的余弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9142a8490de14a87eda628ffa7e28982.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed04b01505bbd8a4ac0bc12e46f23bf6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/eb73f854e7561c943b460e6c84e26fb5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/933f4fb93c7d071a27d90e5d4941c801.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/11/21/731186a4-9a8d-4d8b-b384-b7bd40488bcb.png?resizew=149)
(Ⅰ)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1399e7ae0b2decaafc62a5cdffb15522.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
(Ⅱ)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/da174d0bf75f3be80198a7a9586b0ae9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/445b51117626fbd3373e32acc514c64b.png)
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【推荐1】如图,四棱锥P−ABCD的底面ABCD是边长为2的正方形,
.
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/31/6fe13a00-c920-4d90-b1a3-0012c255ab33.png?resizew=171)
(1)证明:PC=PD;
(2)当直线PA与平面PCD所成角的正弦值最大时,求此时二面角P−AB−C的大小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f01178cfd892d82642d9e055812f3e2a.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/31/6fe13a00-c920-4d90-b1a3-0012c255ab33.png?resizew=171)
(1)证明:PC=PD;
(2)当直线PA与平面PCD所成角的正弦值最大时,求此时二面角P−AB−C的大小.
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解答题-证明题
|
适中
(0.65)
解题方法
【推荐2】如图所示,在斜三棱柱
中,底面是等腰三角形,
,侧面
底面ABC.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/5/e8953750-cb1d-4a7a-80ac-a744d7c7a49f.png?resizew=156)
(1)若D是BC的中点,求证:
;
(2)过侧面
的对角线
的平面交侧棱于M,若
,求证:截面
侧面
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73a9ad711b25c36dae0c2a2cedff9954.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50d9bdbbdfabc737323692c796e41930.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/7/5/e8953750-cb1d-4a7a-80ac-a744d7c7a49f.png?resizew=156)
(1)若D是BC的中点,求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/38c0e83c03e0864ff00b26af15ff7056.png)
(2)过侧面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58cc6184b191e6da43911e701121517e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0d8772aa893a9c1d40f714cb25701701.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bea287616019d94c51c7362627a38eba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99d020167b334dfda0dce811c519d323.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/58cc6184b191e6da43911e701121517e.png)
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(0.65)
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【推荐3】如图,在四棱锥
中,底面
是边长为2的菱形,
,
.
;
(2)若二面角
为
,求平面
与平面
夹角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0585b6c0f156eecf9662b9846d4eb693.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c6e0b64d25ddd18454f88e40c45d7d8f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8b01fa08bfa35362d4cfabcbe1c01458.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f0063f3f48e49f2970ec7f097567cef5.png)
(2)若二面角
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d399d731913a563e291b817831a0c678.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4a12c461765806bbfb872e7e8aa410c8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/745e0525a41fe2e2a7739c75a942290b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/955e030d649a3c7885071b4bf849993c.png)
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