C2:(y/b)^2-(x/a)^2= 1
E 1= under the radical sign (1+b 2/a 2)
E2= under the root sign (1+A 2/B 2)
e 1+e2=t
t^2=2+a^2/b^2+b^2/a^2+
2t
t^2-2t-(b^2/a^2+a^2/b^2+2)=0
Then find the root.
You can set b 2/a 2+a 2/b 2 = v (greater than or equal to 2).
△=4+
4v
+8= 12+4v
Tmin = (under 2+radical sign (12+4V))/2 ((under 2-radical sign (12+4v))/2) truncation)
So when v takes 2, it is the minimum value.
That is tmin=3.