19-20高二下·上海浦东新·期中
名校
1 . 如图所示的几何体
中,四边形
为菱形,
,
平面
,
.
![](https://img.xkw.com/dksih/QBM/2020/9/9/2546250166607872/2549037600161792/STEM/ece102dfc7714f79a49da97e89487f89.png?resizew=185)
(1)求证:
平面
;
(2)若
,求直线
与平面
所成角的正弦值;
(3)若
,
是
内的一点,求点
到平面
,平面
,平面
的距离的平方和最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9165d9bfbb0f0d19eb482c2a4c1b29b7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c8139d9fd5c670c91aa7dc485366dd1e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a22d6b860f06fe23618b0d3de6768fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/224efa375375f1ac848b0c15ee51aebd.png)
![](https://img.xkw.com/dksih/QBM/2020/9/9/2546250166607872/2549037600161792/STEM/ece102dfc7714f79a49da97e89487f89.png?resizew=185)
(1)求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1c8ccd4181f956f6e0140bf0ab8f0716.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10fc7991ea17d54ff5f4445ac5699463.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/97cf714ffb3fd5917a76b191640b55fe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/10fc7991ea17d54ff5f4445ac5699463.png)
(3)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33ac762a2899a58faa0d3ab44f1281fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a313fa9db2c50907e7341b07cdde8021.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a77303421f4ab74d9026866f35fa5a63.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6541c0cb89f08aa4c937c0beb915e0a7.png)
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