The standard form is (x - h)2<span> = 4p (y - k), where the focus is (h, k + p) and the directrix is y = k - p. If the </span>parabola<span> is rotated so that its vertex is (h,k) and its axis of symmetry is parallel to the x-axis, it has an </span>equation<span> of (y - k)</span>2<span> = 4p (x - h), where the focus is (h + p, k) and the directrix is x = h - p.</span>
