别在半路丢下我
幼苗
共回答了22个问题采纳率:90.9% 举报
(1)
![](https://img.yulucn.com/upload/2/5d/25d84179929e07a9ed7fba9a7dd09232_thumb.jpg)
=±1.(2) AB =
![](https://img.yulucn.com/upload/b/52/b523cd86226664c87d00e8d1c73e2c6d_thumb.jpg)
(3)直线 AB 的斜率 k
AB = 1. AB 的方程为 x – y +1 = 0.当
![](https://img.yulucn.com/upload/2/5d/25d84179929e07a9ed7fba9a7dd09232_thumb.jpg)
= –1时, AB 的方程为 x – y -1 = 0.
1)圆 x
2 + y
2 + 2 x – 2 y = 0按向量
![](https://img.yulucn.com/upload/c/0c/c0c289cc01666e32c647cf70dfdb9f8a_thumb.jpg)
= (1,–1)平移,得到圆 O : x
2 + y
2 = 2,所以半径 r =
![](https://img.yulucn.com/upload/1/58/1586091bc794ec39f32bfd80949f5287_thumb.jpg)
.∵|
![](https://img.yulucn.com/upload/9/b7/9b7e254daf6aa27b386664b412173c62_thumb.jpg)
| = |
![](https://img.yulucn.com/upload/2/5d/25d84179929e07a9ed7fba9a7dd09232_thumb.jpg)
a | =
![](https://img.yulucn.com/upload/1/58/1586091bc794ec39f32bfd80949f5287_thumb.jpg)
,即|
![](https://img.yulucn.com/upload/2/5d/25d84179929e07a9ed7fba9a7dd09232_thumb.jpg)
|| a | =
![](https://img.yulucn.com/upload/1/58/1586091bc794ec39f32bfd80949f5287_thumb.jpg)
,∴
![](https://img.yulucn.com/upload/2/5d/25d84179929e07a9ed7fba9a7dd09232_thumb.jpg)
=±1.
(2)取 AB 中点 D ,连结 OD ,∵
![](https://img.yulucn.com/upload/1/87/187bd5b8ff4fcfa614de61cf5ed5c7b2_thumb.jpg)
,由
![](https://img.yulucn.com/upload/2/2e/22ee818df0658a4b835ea2ef304676d6_thumb.jpg)
可得
![](https://img.yulucn.com/upload/8/29/8299d6ac9f8b5888d7c5f21124d1c6fd_thumb.jpg)
,
∴
![](https://img.yulucn.com/upload/d/ce/dcec67cc8f43c22510d5eeee94eed642_thumb.jpg)
,又∵ OD ⊥ AB ,∴ AB =
![](https://img.yulucn.com/upload/b/52/b523cd86226664c87d00e8d1c73e2c6d_thumb.jpg)
.
(3)当
![](https://img.yulucn.com/upload/2/5d/25d84179929e07a9ed7fba9a7dd09232_thumb.jpg)
=1时,
![](https://img.yulucn.com/upload/b/93/b93018d0bbdffaa4458ccd74054f257e_thumb.jpg)
= (1,–1),设 D 点坐标为( x , y ),则
![](https://img.yulucn.com/upload/a/5c/a5cc62fe6c6f50ce42271994e3db877e_thumb.jpg)
,又∵直线 AB 的斜率 k
AB = –
![](https://img.yulucn.com/upload/9/9a/99aeabc7d884034343d5620b9685a541_thumb.jpg)
= 1. AB 的方程为 x – y +1 = 0.
同理当
![](https://img.yulucn.com/upload/2/5d/25d84179929e07a9ed7fba9a7dd09232_thumb.jpg)
= –1时, AB 的方程为 x – y -1 = 0.
1年前
10