
Coordinates of the centre will be (2,1) Equation of circle will be $\begin{aligned}
& (\mathrm{x}-2)^2+(\mathrm{y}-1)^2=1 \
& \mathrm{QC}=\sqrt{(5-2)^2+(5-1)^2} \
& \mathrm{QC}=5
\end{aligned}shortestdistance\begin{aligned}
& =\mathrm{RQ}=\mathrm{CQ}-\mathrm{CR} \
& =5-1 \
& =4
\end{aligned}$