1. You probably have determined the coordinates of the focus as S(0, 1).

2. The equation of the parabola is .

That means the slope of the tangent to the parabola is calculated by

3. Let be a point on the parabola. The tangent at P to the parabola has the equation:

4. The normal in P has the slope . Since the normal passes through P too it has the equation:

5. Now determine the point of intersection of the parabola and the normal.

6. Show that that means the angle .