Since the focus and vertex are above and below each other, rather than side by side, I know that this ellipse must be taller than it is wide. Then a2 will go with the y part of the equation. Also, since the focus is 3 units above the center, then c = 3; since the vertex is 4 units above, then a = 4. The equation b2 = a2 – c2 gives me 16 – 9 = 7 = b2. (Since I wasn't asked for the length of the minor axis or the location of the co-vertices, I don't need the value of b itself.) Then my equation is: