Do \(I\in\Delta\Rightarrow\) tọa độ có dạng: \(I\left(1-3t;-2+4t\right)\)
\(\Rightarrow\overrightarrow{AI}=\left(2-3t;-9+4t\right)\)
\(IA=\sqrt{\left(2-3t\right)^2+\left(-9+4t\right)^2}=4\)
\(\Leftrightarrow\left(2-3t\right)^2+\left(-9+4t\right)^2=16\)
\(\Leftrightarrow25t^2-84t+69=0\)
\(\Leftrightarrow...\)