(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.