and 
and transverse axis of length 6.
We must interpret the information given to us in the above problem. First, we see that the foci are 18 units apart (and live on the y--axis). Thus, we have
Moreover,
since the length of the transverse axis is 6. Since the center of the hyperbola
is at 
, the vertices of the hyperbola must be at 
and 
.
Finally, we just need to find out the value of b. From the
relationship
we know that
This can be simplified to
Thus we see that
Now we can write the standard equation of the hyperbola. It is
Before moving on, note that the eccentricity of this hyperbola is
James A. Sellers