Math problem, help me and show steps, thanks a lot.?
2008-05-28 6:10 pm
find the equation of the line tangent to the circle x^2+y^2 -2x +6y -15 = 0 at the point P(4, -7),
回答 (1)
2008-05-28 6:25 pm
✔ 最佳答案
the center of the circle (O)is (2/2, -6/2) the slope of OP is [1-4]/[-3-(-7)]=-3/4
Let A (x,y) be a point on the tangent
the slope of AP * the slope of OP =-1(AP垂直OP)
so, the slope of AP=4/3
then [x-1]/[y-(-7)]=4/3
3(x-1)=4(y+7)
the ans: 3x-4y-31=0
收錄日期: 2021-04-29 21:44:15
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080528000051KK00533