[tex]\bf \cfrac{(x-{{ h}})^2}{{{ a}}^2}+\cfrac{(y-{{ k}})^2}{{{ b}}^2}=1\qquad \qquad
\cfrac{(x-{{ h}})^2}{{{ b}}^2}+\cfrac{(y-{{ k}})^2}{{{ a}}^2}=1[/tex]
for an ellipse, the major axis, is over the variable with the "a" component, or the greater denominator