解题方法
1 . 在正方体
中,
分别是棱
和
上异于端点的动点,将经过三点
的平面被正方体截得的图形记为
.如图中
时截面图形
为矩形.
(1)在图中作出截面图形
为梯形的情形;(直接画出图形即可,不需说明)
(2)当点
为
中点时,求
与平面
所成角的正弦值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6e09725691ee7851f54c0dee86b2bf55.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c1ae536809b1161fd4e83fdc7f42be96.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d1859959fdb4c5edd8056893f94a10a0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53e97fcdcfd6183b976a61ef3222c607.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5d04ea588f556c3b874b7e68ea69f49e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b94469fd19f40116e2dec334919d6586.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f805768a5ffaf8bdfa4bc3b680aafdc9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b94469fd19f40116e2dec334919d6586.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/11/29/5db5de67-b86d-4aaf-b4be-12f24a3ef879.png?resizew=164)
(1)在图中作出截面图形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b94469fd19f40116e2dec334919d6586.png)
(2)当点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0a851907ada2ac2c3c4880a6736d28a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3ee8456443402a25b1e25d35ff7e1c98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ca48c18021e7be4bbb3e95576e1c1b5f.png)
您最近一年使用:0次
2 . 某同学探究函数![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4426903eb63c0cf1b8e19d97f25398f.png)
的最小值,并确定相应的x的值.先列表如下:
请观察表中y值随x值变化的特点,完成下列问题:((1)(2)问的填空只要写出结果即可)
(1)若
, 则
.(请填写“
, =,
”号);若函数
在区间 (0,2)上递减,则
在区间 上递增;
(2)当
时,![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4426903eb63c0cf1b8e19d97f25398f.png)
的最小值为 ;
(3)根据函数
的有关性质,你能得到函数![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe5effb3053cf609f59178641cd48167.png)
的最大值吗?为什么?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4426903eb63c0cf1b8e19d97f25398f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/118c9c0597d2c72126fbc4cc3927108e.png)
x | … | ![]() | ![]() | 1 | ![]() | 2 | ![]() | 4 | 8 | 16 | … |
y | … | 16.25 | 8.5 | 5 | ![]() | 4 | ![]() | 5 | 8.5 | 16.25 | … |
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/efdfb7f9b4a4e8898702a030c5981dfa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/915b3d29d0c7dd83c188e3ce31f52fc4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be22faef62e7a035eb39a2e020c880e2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/392cdb9d30684cce244bef94b8d861b9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a009fc98a713bd1f25d427a02322464d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4426903eb63c0cf1b8e19d97f25398f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab03556c333ab0b55fe86c937b2a5763.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4fe7d5809da02c15a43a0e9a898b9086.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4ec0618ae3a4fde6d6220010af229b9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4426903eb63c0cf1b8e19d97f25398f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/118c9c0597d2c72126fbc4cc3927108e.png)
(3)根据函数
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe5effb3053cf609f59178641cd48167.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e970b5a89849b870c50b39e97ee3bdf2.png)
您最近一年使用:0次