Maths: how to do, thanks?
回答 (1)
2020-05-09 8:37 pm
✔ 最佳答案
C: x²+y²+6x-3y=0L: y=kx
At the pt. which L touches circle C,
x²+(kx)²+6x-3(kx)=0
(1+k²)x²+(6-3k)x=0
Since L touches circle C at only 1 pt.
△=b²-4ac=0
=> (6-3k)²-4(1+k²)(0)=0
=> (6-3k)²=0
∴ 6-3k=0
So, k=2
收錄日期: 2021-04-24 07:52:10
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20200509120022AApD9wd