23-24高二上·上海·课后作业
1 . 在平面上有如下命题:“若点
为直线
外的一点,则点
在直线
上的充要条件是:存在实数
、
满足
,且
.”类比此命题,给出空间某点在某一平面上的充要条件并加以证明.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df64046e91b047037f19e4032e3b6de3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1100379a4385b9ce064847bc21760adc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37dd0802f896556180545ae356e90c7a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6096acdd2d0ce16e1e45397ec5e365d4.png)
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解题方法
2 . 我们知道,在平面中,给定一点和一个方向可以唯一确定一条直线.如点
在直线l上,
为直线l的一个方向向量,则直线l上任意一点
满足:
,化简可得
,即为直线l的方程.类似地,在空间中,给定一点和一个平面的法向量可以唯一确定一个平面.
(1)若在空间直角坐标系中,
,请利用平面
的法向量求出平面
的方程;
(2)试写出平面
(A,B,C不同时为0)的一个法向量(无需证明),并证明点
到平面
的距离为
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b1dab74e16403e8131f9f5b2a74f3a84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f41c46212d6f61fca9ce215a477ea1d2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdfc3eef2f592a4e93a6968c7f31e32f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2e463b86ed390c317de2383840fde5df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a24f3197942ff7bd44f44651dd9123b2.png)
(1)若在空间直角坐标系中,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f3ad64b23e508734de034ce16e1ebbe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22ce50ba5e349425274f05d46d120a74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/22ce50ba5e349425274f05d46d120a74.png)
(2)试写出平面
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a46e2fbcd9ba92ca62a67fef9d9652db.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab9f353152c7f589c0caf5f964f803ed.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/39f20004bf3d4eb52ec732d8acc65672.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e878d6f51b5830bd59f0d44aa5d8b38.png)
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名校
解题方法
3 . 我们知道,在
中,
,若
为内切圆的圆心,则由
得到,
内切圆的半径
.将此结论类比到空间,得到:在三棱锥
中,
,
,则三棱锥
内切球的半径![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e3ef4881bd7c5860178dbdbc7bba6e3.png)
___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5dc3c15be47864978aeccce8bbae64b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e105760638b22b26ff8bec4354255e4c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/67cdfc4d6fb1528a35ecae1cf8628fef.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/15c0dbe3c080c4c4636c64803e5c1f76.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b41396d66e5b8550bd38c040ec62b32.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4357d5744046d4d44abb09e1ee35fcb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a4447931b753c487d1e8823aee7cc83.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f5b535b3e9eccdad4d0515fb898b07.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d4357d5744046d4d44abb09e1ee35fcb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8e3ef4881bd7c5860178dbdbc7bba6e3.png)
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