已知圆C的圆心在直线L1:2x+y=0,与直线L2:x+y=1相切,且过点A(2,-1).若过点(0,0)的直线L...已知圆C的圆心在直线L1:2x+y=0,与直线L2:x+y=1相切,且过点A(2,-1).若过点(0,0)的直
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![已知圆C的圆心在直线L1:2x+y=0,与直线L2:x+y=1相切,且过点A(2,-1).若过点(0,0)的直线L...已知圆C的圆心在直线L1:2x+y=0,与直线L2:x+y=1相切,且过点A(2,-1).若过点(0,0)的直](/uploads/image/z/8628949-37-9.jpg?t=%E5%B7%B2%E7%9F%A5%E5%9C%86C%E7%9A%84%E5%9C%86%E5%BF%83%E5%9C%A8%E7%9B%B4%E7%BA%BFL1%EF%BC%9A2x%EF%BC%8By%EF%BC%9D0%2C%E4%B8%8E%E7%9B%B4%E7%BA%BFL2%EF%BC%9Ax%EF%BC%8By%EF%BC%9D1%E7%9B%B8%E5%88%87%2C%E4%B8%94%E8%BF%87%E7%82%B9A%EF%BC%882%2C%EF%BC%8D1%EF%BC%89.%E8%8B%A5%E8%BF%87%E7%82%B9%EF%BC%880%2C0%EF%BC%89%E7%9A%84%E7%9B%B4%E7%BA%BFL...%E5%B7%B2%E7%9F%A5%E5%9C%86C%E7%9A%84%E5%9C%86%E5%BF%83%E5%9C%A8%E7%9B%B4%E7%BA%BFL1%EF%BC%9A2x%EF%BC%8By%EF%BC%9D0%2C%E4%B8%8E%E7%9B%B4%E7%BA%BFL2%EF%BC%9Ax%EF%BC%8By%EF%BC%9D1%E7%9B%B8%E5%88%87%2C%E4%B8%94%E8%BF%87%E7%82%B9A%EF%BC%882%2C%EF%BC%8D1%EF%BC%89.%E8%8B%A5%E8%BF%87%E7%82%B9%EF%BC%880%2C0%EF%BC%89%E7%9A%84%E7%9B%B4)
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已知圆C的圆心在直线L1:2x+y=0,与直线L2:x+y=1相切,且过点A(2,-1).若过点(0,0)的直线L...已知圆C的圆心在直线L1:2x+y=0,与直线L2:x+y=1相切,且过点A(2,-1).若过点(0,0)的直
已知圆C的圆心在直线L1:2x+y=0,与直线L2:x+y=1相切,且过点A(2,-1).若过点(0,0)的直线L...
已知圆C的圆心在直线L1:2x+y=0,与直线L2:x+y=1相切,且过点A(2,-1).若过点(0,0)的直线L3截圆C所得弦长为2,求直线L3的方程
已知圆C的圆心在直线L1:2x+y=0,与直线L2:x+y=1相切,且过点A(2,-1).若过点(0,0)的直线L...已知圆C的圆心在直线L1:2x+y=0,与直线L2:x+y=1相切,且过点A(2,-1).若过点(0,0)的直
(x-k)^2+(y+2k)^2=r^2,又r=|k-2k-1|/√2,以点A在圆上代入得k=1
即求圆心点到直线距离为√(r^2-1)
设直线为y=λx,则有|-2-λ|/√(1+λ^2)=r
解得λ=±√2,直线L3的方程y=±√2x
设圆C的圆心为(x0,y0)
2x0+y0=0
((x0-2)^2+(y0+1)^2)^(1/2)=∣x0+y0+1∣/(2)^(1/2)
解出,x0=1,y0=-2
由∣k+2∣/(k^2+1)^(1/2)=1
解出k=-3/4,直线L3的方程是y=-3x/4,另一条是y轴