As shown in the diagram below: \(C\) is the parabola with equation \(y=x^2\); \(P\) is the point \((0,1)\); \(Q\) is the point \((a,a^2)\) on \(C\); \(L\) is the normal to \(C\) which passes through \(Q\).
Find the equation of \(L\).
For what values of \(a\) does \(L\) pass through \(P\)?
Determine \(\big |QP\big |^2\) as a function of \(a\), where \(\big |QP\big |\) denotes the distance from \(P\) to \(Q\).
Find a point \(R\), in the \(xy\)-plane but not on \(C\), such that \(\big |RQ\big |\) is smallest for a unique value of \(a\). Briefly justify your answer.