Length of major axis = 26; foci = ().

Since the foci are on the x-axis, the major axis is along the x-axis.

Therefore, the equation of the ellipse will be of the form =1, where a is the semi-major axis.

Accordingly, 2a =26 a = 13 and c=5.

It is known that a² = b²+c².

13² = b²+4²

169 = b² + 25

b² = 169 – 25

b = = 12

Thus, the equation of the ellipse is =1 or = 1.