The standard equation for a hyperbola with a horizontal transverse axis is
(x-h)^2/a^2 - (y-k)^2/b^2 = 1 . The center is at (h, k) . The distance between the vertices is 2a . The distance between the foci is 2c and c^2 = a^2 + b^2. Therefore,
8^2 = 6^2 + b^2
b = 2√7
Assuming it is located at the origin.
(x-h)^2/a^2 - (y-k)^2/b^2 = 1
(x)^2/6^2 - (y)^2/(2√7)^2 = 1
x^2/36 - y^2/28 = 1
