Question

How far apart are the foci of an ellipse with a major axis of 26 feet and a minor axis of 24 feet?

Answer 1

The distance should be 10 feet

Answer 2

Let the major axis = 2a , and the minor axis = 2b
∴ a = 26/2 = 13    and   b = 24/2 = 12
and the equation of foci:
c² = a² - b²
    = 13² - 12² = 169 - 144 = 25
∴ c = √25 = 5

∴ The distance between the foci = 2 * 5 = 10