Find the distance ?

Geometry Level pending

The tangent at the point $$P(x',y')$$ to the parabola $$y^2 = 4ax$$ meets the parabola $$y^2 =4a(x+b)$$ at points $$R$$ and $$Q$$ . The distance of the mid point of $$QR$$ from $$P$$ is?

×