The standard ellipse $x^2$/$a^2$ + $y^2$/$b^2$ = 1 has major axis along x-axis when a > b and along y-axis when b > a. The critical first step in any problem is identifying which denominator is larger — that denominator is $a^2$. When a > b: foci (+/-c, 0), vertices (+/-a, 0), co-vertices (0, +/-b), directrices x = +/-a/e, LR = 2$b^2$/a. When b > a: foci (0, +/-c), vertices (0, +/-b), directrices y = +/-b/e, LR = 2$a^2$/b. The relation $c^2$ = $a^2$ - $b^2$ (always: $larger^2$ - $smaller^2$) gives eccentricity e = $\frac{c}{a}$ $\frac{or c}{b for vertical major axis}$. The shifted ellipse (x-h)^2/$a^2$ + (y-k)^2/$b^2$ = 1 has centre (h, k) with all parameters translated accordingly.