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已知圆O1:(x-1)^2+(y-1)^2=4,圆O2:(x-3)^2+(y+4)^2=25(1)判断两圆的位置关系

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已知圆O1:(x-1)^2+(y-1)^2=4,圆O2:(x-3)^2+(y+4)^2=25(1)判断两圆的位置关系
(2)若两圆相交,求公共弦所在直线方程及公共弦的长.
已知圆O1:(x-1)^2+(y-1)^2=4,圆O2:(x-3)^2+(y+4)^2=25(1)判断两圆的位置关系
O1:(x-1)^2+(y-1)^2=4 (1)
centre (1,1),radius =2
O2:(x-3)^2+(y+4)^2=25 (2)
centre(3,4),radius =5
(2) -(1)
-4x+8 + 10y+15 = 21
2x-5y = 1
x = (1+5y)/2 (3)
sub (3) into (1)
((1+5y)/2-1)^2+(y-1)^2=4
(5y-1)^2+4(y-1)^2=16
29y^2-18y-11=0
(29y+11)(y-1)=0
y=1 or -11/29
y =1 ,x=3
y=-11/29,x=-13/29
length of the cord
=√[(3+13/29)^2 +(1+11/29)^2]
=20√29/29
equation of the cord
(y-1)/(x-3) = (-11/29-1)/(-13/29-3)
= 2/5
5(y-1) = 2(x-3)
2x-5y-1=0
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