I've got a one mark question on an assignment, so 'logic' dictates that it should be simple, right? But I just don't get it.
I've got the variable point P(2at, at^2), which lies on the parabola x^2=4at
I've already proven that the equation of the normal at P is x+ty=at^3+2at
Now, based on that, I have to find the co-ordinates of Q (also on the parabola), whose normal is perpendicular to the normal at P.
The next part of the assignment gives me the point at which the two normals intersect (R (a[t-1/t] , a[t^2+1+1/t^2]), so I know that the equation of QR is y=tx+a/t^2+a, but I seeing as that is backwards-engineering from a 4 mark question, there's got to be something I'm missing in the "find Q" one.