11旁写
幼苗
共回答了24个问题采纳率:83.3% 举报
(1)详见解析;(2)该简单几何体的体积
![](https://img.yulucn.com/upload/f/aa/faa73206e36b40c34fbbecb8e1edd1fe_thumb.jpg)
.
试题分析:(1)欲证平面
![](https://img.yulucn.com/upload/a/5d/a5dc4c93d5fb503fa19fa6238d348940_thumb.jpg)
⊥平面
![](https://img.yulucn.com/upload/3/fa/3faaaf26781e069dad87b5848ee4aa68_thumb.jpg)
,证明面面垂直,先证线面垂直,即证一个平面过另一个平面的垂线,本题根据面面垂直的判定定理可知在平面
![](https://img.yulucn.com/upload/3/fa/3faaaf26781e069dad87b5848ee4aa68_thumb.jpg)
内找一条直线与平面
![](https://img.yulucn.com/upload/a/5d/a5dc4c93d5fb503fa19fa6238d348940_thumb.jpg)
垂直,而由已知
![](https://img.yulucn.com/upload/5/a2/5a2c2a66c055d02b6f875631aa78fe5f_thumb.jpg)
平面
![](https://img.yulucn.com/upload/a/5d/a5dc4c93d5fb503fa19fa6238d348940_thumb.jpg)
,
![](https://img.yulucn.com/upload/0/1f/01f2f1d4edae7b238ebc2deaa86ead32_thumb.jpg)
,可得
![](https://img.yulucn.com/upload/a/4a/a4a6ae2cdb2b5a03e53b9b1b80e86ca8_thumb.jpg)
平面
![](https://img.yulucn.com/upload/a/5d/a5dc4c93d5fb503fa19fa6238d348940_thumb.jpg)
,从而可得平面
![](https://img.yulucn.com/upload/a/5d/a5dc4c93d5fb503fa19fa6238d348940_thumb.jpg)
⊥平面
![](https://img.yulucn.com/upload/3/fa/3faaaf26781e069dad87b5848ee4aa68_thumb.jpg)
;(2)所求简单组合体的体积进行分
![](https://img.yulucn.com/upload/5/a5/5a5fbf18b896e879c6f2d6c344fa4644_thumb.jpg)
,然后利用体积公式进行求解,关键是几何体的高的求解.
试题解析:(1)证明:∵ DC
![](https://img.yulucn.com/upload/8/5b/85b4dc9fd4fca2123ad1dd71f4f0d717_thumb.jpg)
平面ABC ,
![](https://img.yulucn.com/upload/d/07/d07f673a425e5ec5a8b272ff09b6286e_thumb.jpg)
平面ABC
∴
![](https://img.yulucn.com/upload/2/0b/20b28a2dc2a2e3482b117015d91bda36_thumb.jpg)
. .1分
∵AB是圆O的直径 ∴
![](https://img.yulucn.com/upload/3/b3/3b3048dcd11f95190963e01f034caa42_thumb.jpg)
且
∴
![](https://img.yulucn.com/upload/8/5b/85b4dc9fd4fca2123ad1dd71f4f0d717_thumb.jpg)
平面ADC. 3分
∵四边形DCBE为平行四边形 ∴DE//BC
∴
![](https://img.yulucn.com/upload/8/5b/85b4dc9fd4fca2123ad1dd71f4f0d717_thumb.jpg)
平面ADC 5分
又∵
![](https://img.yulucn.com/upload/6/52/65293a59b3d9300603e6855906487943_thumb.jpg)
平面ADE∴平面ACD
![](https://img.yulucn.com/upload/8/5b/85b4dc9fd4fca2123ad1dd71f4f0d717_thumb.jpg)
平面
![](https://img.yulucn.com/upload/3/fa/3faaaf26781e069dad87b5848ee4aa68_thumb.jpg)
..6分
(2)所求简单组合体的体积:
∵
![](https://img.yulucn.com/upload/6/6b/66b54acf5043b6b18efc52be4990bff1_thumb.jpg)
,
![](https://img.yulucn.com/upload/1/87/187c12e325c38ea522a6b0c1502b6883_thumb.jpg)
,
∴
![](https://img.yulucn.com/upload/e/9d/e9df73715ec2e34f1ed90d8aa926f789_thumb.jpg)
,
![](https://img.yulucn.com/upload/d/37/d372b672a0f9c9551e724880643a4d57_thumb.jpg)
10分
∴
∴该简单几何体的体积
![](https://img.yulucn.com/upload/f/aa/faa73206e36b40c34fbbecb8e1edd1fe_thumb.jpg)
12分
1年前
9