Conic Sections

Let T be the tangent to the parabola y2=16x at the point (64,32). Let L be the tangent to the same parabola at another point (x1, y1) on the parabola. If L and T are perpendicular to each other, then the distance between the point (x1, y1) and the focus of the parabola, is

1. 154
2. 4
3. 174
4. 5