Slope of Tangent at Parameter $$t$$

Let $$T$$ be the tangent to the parabola $$y^2=16x$$ at the point $$(64,32)$$. Let $$L$$ be the tangent to the same parabola at another point $$(x_1,\,y_1)$$ on the parabola. If $$L$$ and $$T$$ are perpendicular to each other, then the distance between the point $$(x_1,\,y_1)$$ and the focus of the parabola, is