If the line y = k - 2x divides the circle x^2+y^2 - 2x- 4y - 5 = 0 into two equal parts, find k.
thanks~
plz solve the maths !!
2008-11-27 5:21 am
回答 (2)
2008-11-27 5:45 am
✔ 最佳答案
Circle: x2 + y2 - 2x - 4y - 5 = 0
Centre = (-(-2)/2, -(-4)/2) = (1, 2)
The line y = k - 2x divides the circle into two equal parts.
The line y = k - 2x must pass through the centre (1, 2) of the circle.
(2) = k - 2(1)
2 = k - 2
k = 4
=
2008-11-27 5:51 am
you know y = k - 2x cut a circle in to 2 equal. it means y = k - 2x is the diameter(which passes through the centre.)
from the circle>>>(h,k)=(-2/-2,-4/-2)=(1,2)
then the centre must be forever fix with the diameter. therefore
2=k-2(1)
solve it you can get the anwser
from the circle>>>(h,k)=(-2/-2,-4/-2)=(1,2)
then the centre must be forever fix with the diameter. therefore
2=k-2(1)
solve it you can get the anwser
參考: F5 student too
收錄日期: 2021-04-23 23:07:24
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