CDF of Euclidean distance between two points.

CDF of Euclidean distance between two points.

2-D plane, a circle $\text{C}_0$ of radius $R$ centered at $A(0,0)$, $N$
random points $D_i(x_i,y_i),i=1\dots N$ are independently uniformly
distributed in $\text{C}_0$.
Choose the point $D_s$ from $D_i$ which has the smallest Euclidean
distance to point $A$, i.e., $$s = \mathop{\arg\min}_{i=1\dots
N}\sqrt{x_i^2+y_i^2},\\ d_s=\min_{i=1\dots N}\sqrt{x_i^2+y_i^2}. $$
I know that the CDF of $d_s$ is
$$F_{d_s}(r)=1-\left(1-\frac{r^2}{R^2}\right)^N,0\leq r\leq R.$$
If there is another point $P(a,0),a>R$, the Euclidean distance from $D_s$
to $P$ is $$d_{sp}=\sqrt{(x_s-a)^2+y_s^2}.$$
How can I find the CDF or PDF of $d_{sp}$ ?
Thanks a lot!