\(C\in d\Rightarrow C\left(xo;\dfrac{-2xo+1}{3}\right);AB\) \(nhận\overrightarrow{AB}\) \(làVTCP\Rightarrow\overrightarrow{u}=\left(-1;3\right)\Rightarrow\overrightarrow{n}=\left(3;1\right)\Rightarrow ptAB:3\left(x-1\right)+y-2=0\Leftrightarrow3x+y-5=0\)
\(d\left(C;AB\right)=\sqrt{10}=\dfrac{\left|3xo+\dfrac{-2xo+1}{3}-5\right|}{\sqrt{3^2+1}}\)
\(\Leftrightarrow\left|\dfrac{7xo-14}{3}\right|=10\Leftrightarrow\left[{}\begin{matrix}\dfrac{7xo-14}{3}=10\Leftrightarrow xo=\dfrac{44}{7}\Rightarrow C\left(\dfrac{44}{7};-\dfrac{27}{7}\right)\\\dfrac{7xo-14}{3}=-10\Leftrightarrow xo=-\dfrac{16}{7}\Rightarrow C\left(-\dfrac{16}{7};-\dfrac{25}{21}\right)\end{matrix}\right.\)
