For the ellipse E, the eccentricity is eE=23 and the directrices are x=±eEaE=±346.
The semi-major axis aE is given by:
aE=eE×346=23×346=6122=22
The semi-minor axis bE is given by:
bE2=aE2(1−eE2)=(22)2(1−43)=8×41=2⇒bE=2
For the hyperbola H:a2x2−b2y2=1, its eccentricity eH is equal to the semi-major axis of E:
eH=aE=22
The length of the latus rectum of H is equal to the length of the minor axis of E (2bE):
a2b2=2bE=22⇒b2=2a
Using the standard relation for a hyperbola b2=a2(eH2−1), we substitute b2 and eH:
2a=a2((22)2−1)
2a=a2(8−1)=7a2
Since a>0, dividing by a gives:
a=72
The distance between the foci of the hyperbola H is 2aeH:
2aeH=2×72×22=78
Answer: 78