Probability

Paragraph for next 2 questions
Consider the lines L1 and L2 defined by L1:x√2+y−1=0 and L2:x√2−y+1=0
For a fixed constant λ, let C be the locus of a point P such that the product of the distance of P from L1 and the distance of P from L2 is λ2. The line y=2x+1 meets C at two points R and S, where the distance between R and S is √270.
Let the perpendicular bisector of RS meet C at two distinct points R′ and S′. Let D be the square of the distance between R' and S'.