Parabola

If point P is $$(a{t^2},2at)$$,then the length of the focal chord PQ is 
$$a{\left( {t + \cfrac{1}{t}} \right)^2}$$.
The equation of the normal to the parabola, $$x^{2}=8y$$ at $$x=4$$ is:
The shortest distance between the line $$y-x-1$$ and the curve $$x={y}^{2}$$
An arc is in the form of parabola with its axis vertical. The arch is 10 m high and 5 m wide at the base. How wide is it 2 m form the vertex of the parabola 
The polar of the point $$(2,1)$$ with respected to the parabola $$y^2 = 6x$$, is