两圆圆F1(-√5,0)F2(√5,0) 设圆C半径R 若与圆F1内切与圆F2外切满足 CF1+2=R=CF2-2 所CF2-CF1=4 若与圆F2内切与圆F1外切满足 CF1-2=R=CF2+2 所CF1-CF2=4 所C点满足|CF1-CF2|=4
