Bring the straight line into the ellipse, and sort out the quadratic equation of x, with coefficients of (A +b), 2a and (A -a *b) respectively. Pay special attention to the discriminant δ≥ 0 and get (Party A+Party B) ≥ 1.

And AB is a circle with a diameter passing through the origin, so OA and OB are perpendicular to each other. A(x 1, x 1+ 1) and B(x2, x2+l) are arranged as 2x 1x 2+(XL+x2)+65438+. If it is converted into (A-1)*(b-1)=l, you can look at the equation in which a and b are variables, (it is an inverse ratio curve with the center moving to the point (1, l)).

Now we deal with the range of eccentricity, that is, (6/9) ≤ (Party C/Party A) ≤(8/9), so (1/9) ≤ (Party B/Party A) ≤(3/9). Combined with the above-mentioned translation inverse proportional curve, b = (3/9) a.

If you don't understand, please keep asking questions, but please do more work and think for yourself.