Gọi \(Q\left(a;0\right)\Rightarrow\left\{{}\begin{matrix}\overrightarrow{AQ}=\left(a-2;-3\right)\\\overrightarrow{AB}=\left(2;-2\right)\end{matrix}\right.\)
ABQ vuông tại A \(\Leftrightarrow\overrightarrow{AQ}.\overrightarrow{AB}=0\)
\(\Leftrightarrow2\left(a-2\right)+6=0\) \(\Rightarrow a=-1\)
\(\Rightarrow Q\left(-1;0\right)\)
b. Gọi \(H\left(0;b\right)\Rightarrow\overrightarrow{AH}=\left(-2;b-3\right)\)
\(AH=\sqrt{13}\Leftrightarrow4+\left(b-3\right)^2=13\)
\(\Leftrightarrow\left(b-3\right)^2=9\Rightarrow\left[{}\begin{matrix}b=0\\b=6\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}H\left(0;0\right)\\H\left(0;6\right)\end{matrix}\right.\)
