如图,棱长为1的正方体
中,点
为
的中点,则下列说法正确的是____________ .
与
为异面直线
②
与平面
所成角的正切值为![](https://staticzujuan.xkw.com/quesimg/Upload/formula/821309f088a175c00dc0f4828334503d.png)
③过
三点的平面截正方体所得两部分的体积相等
④线段
在底面
的射影长为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11ddc92d84d188c66b435664a7e7b5a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e168672b47d7e64dc1b404f8882c7dcf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/821309f088a175c00dc0f4828334503d.png)
③过
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dc05a73194804cfd0465d00c91721f8c.png)
④线段
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e6e490f703eb6c9bb1278c78ebc2d661.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf298f00799cbf34b4db26f5f63af92f.png)
更新时间:2023-12-29 12:00:21
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【推荐1】棱长为1的正方体
中,若E、F、G分别是AB、AD、
的中点,则该正方体的过E、F、G的截面面积为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/56f7ba05c54b3de1f4378f7c8eb58328.png)
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解题方法
【推荐2】已知正方体
的棱长为
,点E,F,G分别为棱AB,
,
的中点,下列结论中,正确结论的序号是___________ .
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/9/f1744910-99d5-4cb6-8fd9-15067b27b5c6.png?resizew=198)
①过E,F,G三点作正方体的截面,所得截面为正六边形;
②
平面EFG;
③
平面
;
④异面直线EF与
所成角的正切值为
;
⑤四面体
的体积等于
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f66fb71b75b63594ebeeeebd1963eed5.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/9/f1744910-99d5-4cb6-8fd9-15067b27b5c6.png?resizew=198)
①过E,F,G三点作正方体的截面,所得截面为正六边形;
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0efd3ad8ddccdc251c85533353d2633f.png)
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4645450a006f2c20087486d0833afbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13cfdc6224181d44e63aab43ddaf07ef.png)
④异面直线EF与
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fe734023d4e70010a6b2cc3267cb86e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8d5989c84e320b504511f23eeb6e7357.png)
⑤四面体
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68ac02c2f91cadb1e328bc6ab9b9c491.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4aec67c4c83e4955f36ec34afb19df83.png)
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【推荐1】给出下列结论:
①设平面α与平面β相交于直线m,直线a在平面α内,直线b在平面β内,且b⊥m,则α⊥β是a⊥b的必要不充分条件.
②在区间[-1,1]上随机取一个数x,则
的值介于0到
之间的概率为![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
③从以正方体的顶点连线所成的直线中任取两条,则所取两条直线为异面直线的概率为![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f053ede9bc7e812d21128cc31a59ad3.png)
④将4个相同的红球和4个相同的蓝球排成一排,从左到右每个球依次对应的序号为1,2,3,…,8,若同色球之间不加区分,则4个红球对应的序号之和小于4个蓝球对应的序号之和的排列方法种数为31.
其中正确结论的序号为___________ .
①设平面α与平面β相交于直线m,直线a在平面α内,直线b在平面β内,且b⊥m,则α⊥β是a⊥b的必要不充分条件.
②在区间[-1,1]上随机取一个数x,则
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a2e51b2fb9409bd4790ca95eb01fa8d1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f89eef3148f2d4d09379767b4af69132.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4dac452fbb5ef6dd653e7fbbef639484.png)
③从以正方体的顶点连线所成的直线中任取两条,则所取两条直线为异面直线的概率为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f053ede9bc7e812d21128cc31a59ad3.png)
④将4个相同的红球和4个相同的蓝球排成一排,从左到右每个球依次对应的序号为1,2,3,…,8,若同色球之间不加区分,则4个红球对应的序号之和小于4个蓝球对应的序号之和的排列方法种数为31.
其中正确结论的序号为
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【推荐2】以下命题:
①在平面内的一条直线,如果和这个平面的一条斜线的射影垂直,那么它和这条斜线垂直;
②已知平面
的法向量分别为
,则
;
③两条异面直线所成的角为
,则
;
④直线与平面所成的角为
,则
.
其中正确的命题是_____________________ (填上所有正确命题的序号).
①在平面内的一条直线,如果和这个平面的一条斜线的射影垂直,那么它和这条斜线垂直;
②已知平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4e288596fa3811dd2c17bded60e82e7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/436f09f5dbfe95803d8f123893a33f7f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9512a65aa2dd4d2f83d969d3403c3c6e.png)
③两条异面直线所成的角为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c24095e409b025db711f14be783a406c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3712ce4cde0a2c2f4a3d50ff2caca730.png)
④直线与平面所成的角为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/27ed74dbeba7d418a559f9c97c1df414.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6b48c2bd07186927b1524dd44039bfb4.png)
其中正确的命题是
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【推荐1】在正三棱锥
中,M、N分别是校SA、AB的中点,且
,若侧棱
,则正三棱锥
外接球的体积是______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41e5db1d2fd912f77923e4c120a7dc19.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/84bd173466089f8e523dc02808239daf.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f8300bca7b13f8487061c5d6d2e82802.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/41e5db1d2fd912f77923e4c120a7dc19.png)
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【推荐2】如图,正三棱柱
的棱长均为2,点M是侧棱
的中点,过
与平面
垂直的平面与侧面
的交线为l,则直线l与直线
所成角的余弦值为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/42d3a82b8e587ee890467835bc4e854c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2777840758e70e7dbbc18cef8f3d6d2b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15b20bec6da0e92b220021ab497e1ccc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/29f491a794b9ac1a85a18c87ecee616c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab3e0dba5705e1d749cfb21ebbb2ed93.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0dc5c9827dfd0be5a9c85962d6ccbfb1.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/8/eefd829d-7832-4428-a5bd-ed6a2f87c17f.png?resizew=141)
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解题方法
【推荐1】已知
是正方体
棱
的中点,则直线
与平面
所成的角的大小等于________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d88bf46ad08f9677c37eed1d0369329.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9ce1b066f8869d0ff4513f7a99745125.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
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【推荐2】将正方形
沿对角线
折成直二面角
,有如下四个结论:
①
;
②
是等边三角形;
③
与平面
所成的角为
;
④
与
所成的角为
.
其中错误的结论是____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f1854ba6cc92481d7a616bd2788a47e.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cfc1f76257275ab4b04f9bc913535670.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9f8f01137e92c0f2e63467036ae9cce.png)
③
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca67a5b8f69507c8b80379e86f90a8ce.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d5bca00fa20e6e80480b9d06d2e52ee.png)
④
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2d5bca00fa20e6e80480b9d06d2e52ee.png)
其中错误的结论是
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