Another on Circle: It will make u round and round

A circle M is drawn with its centre on x-axis and pass through Centre of another circle N any of whose points can be given by $( cos (\alpha) , sin ( \alpha )$ . A common tangent to M and N Touch the Circles at Q and R respectively . The $Q(x,y)$ always satisfies $x^{2} = \lambda/ 2015$ . Then $\lambda$ is