Question 193075
The standard forms for ellipses with centers at the origin are:
{{{x^2/a^2 + y^2/b^2 = 1}}} Major axis is horizontal.
{{{y^2/a^2 + x^2/b^2 = 1}}} Major axis is vertical.
One way to remember which is which is; The major axis = 2a and is longer than the minor axis (2b), so...if the larger denominator ({{{a^2)}}}) is under the {{{x^2}}} term, the major axis is horizontal.  If the larger denominator ({{{a^2}}}) is under the {{{y^2}}} term, the major axis is vertical.