Find the centre and radius of the circle $x^2+y^2-2x-4y=9$.

Question

$\begin{array}{1 1}(a)\;(1,2),\sqrt{14}\\(b)\;(-1,-2),\sqrt{13}\\(c)\;(1,4),\sqrt{11}\\(d)\;(2,4),\sqrt{15}\end{array}$