What is the equation of the parabola with focus (1 3) and vertex at (3 3)?

The equation of a parabola can be determined using its focus and vertex. Given the focus at (1, 3) and the vertex at (3, 3), the parabola opens horizontally since the x-coordinate of the focus is less than that of the vertex. The standard form for a horizontally opening parabola is ((y - k)^2 = 4p(x - h)), where (h, k) is the vertex and p is the distance from the vertex to the focus. Here, (p = -2) (the focus is 2 units left of the vertex), so the equation is ((y - 3)^2 = -8(x - 3)).