(2) The idea is simple and it is a bit difficult to calculate. The equation of elliptic circle can be sorted by 2x from eccentricity.

2

+3y

2

=6c

2

Set a straight line again

Y = k (x-3c)。 Get at the same time.

(2+3k

2

)x

2

- 18k

2

cx+27k

2

c

2

-6c

2

= 0 let A(X 1, Y 1)B(X2, Y2). Find X 1 by Vader theorem.

X2, represented by k, can be found by substituting into the formula of two products. Give the idea first = = the writing process.