focus | (f_x, f_y) directrix | y = -f_x^2/(f_y - v_y) - (x f_x)/(f_y - v_y) + (3 f_x v_x)/(f_y - v_y) - (2 v_x^2)/(f_y - v_y) + (x v_x)/(f_y - v_y) - f_y + 2 v_y (assuming vertex (v_x, v_y))

(drawn with rotation angle 0°)