1.Find the equaion of the circle passing through the points(0,0),(1,0) and (4,2)
2.Find the equation of the circle which passes through the origin and cuts the x-axis and the y-axis with intercepts -5 and 10 respectively.
amaths
2007-11-29 4:57 am
回答 (2)
2007-11-29 5:05 am
✔ 最佳答案
1. Let the equation be x^2 + y^2 + Dx + Ey + F = 0
Sub (0,0), we have F = 0
sub (1,0)
1 + D = 0
D = -1
sub (4,2)
12 + 4 - 4 + 2E = 0
E = -6
therefore the equation should be x^2 + y^2 - x - 6y = 0
2. Let the equation be
x^2 + y^2 + Dx + Ey + F = 0
Sub (0,0), we have F = 0
sub (-5, 0)
25 - 5D = 0
D = 5
sub (0, 10)
100 + 10E = 0
E = -10
therefore the equation should be x^2 + y^2 + 5x -10y = 0
2007-11-29 5:15 am
Let the equation be
x^2+y^2+Dx+Ey+F = 0
sub(0,0)
∴F=0
sub(1,0)
1+D=0
D=-1
sub(4,2)
16+4-4+2E = 0
E = -8
∴the circle is x^2+y^2-x-8y = 0
2.Let the equation be
x^2+y^2+Dx+Ey+F = 0
sub(0,0)
∴F=0
sub x-axis is -5 i.e(-5,0)
25-5D=0
D=5
sub y-axis is 10 i.e(0,10)
100+10E=0
E=-10
∴the circle is x^2 + y^2 + 5x -10y = 0
x^2+y^2+Dx+Ey+F = 0
sub(0,0)
∴F=0
sub(1,0)
1+D=0
D=-1
sub(4,2)
16+4-4+2E = 0
E = -8
∴the circle is x^2+y^2-x-8y = 0
2.Let the equation be
x^2+y^2+Dx+Ey+F = 0
sub(0,0)
∴F=0
sub x-axis is -5 i.e(-5,0)
25-5D=0
D=5
sub y-axis is 10 i.e(0,10)
100+10E=0
E=-10
∴the circle is x^2 + y^2 + 5x -10y = 0
參考: me
收錄日期: 2021-04-29 20:00:18
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https://hk.answers.yahoo.com/question/index?qid=20071128000051KK03339