A parabola may be defined as the set of all points equidistant from a fixed point called the bcus and a fixed line called the directrix. (a) Suppose the focus is located at $(0, p)$ and the directrix has the equation $y=-p,$ determine the equation of this parabola. (b) Suppose the focus is located at

$(0,-p)$ and the directrix has the equation $y=p,$ determine the equation of this parabola.