Do \(M\in\Delta\) nên tọa độ có dạng: \(M\left(m;1-m\right)\)
\(\Rightarrow\overrightarrow{NM}=\left(m+1;-m-2\right)\)
\(\Rightarrow MN^2=\left(m+1\right)^2+\left(-m-2\right)^2=5^2\)
\(\Leftrightarrow m^2+3m-10=0\Rightarrow\left[{}\begin{matrix}m=2\Rightarrow M\left(2;-1\right)\\m=-5\Rightarrow M\left(-5;6\right)\left(loại\right)\end{matrix}\right.\)
Vậy \(M\left(2;-1\right)\)

