$
\begin{array}{l}
{{M}{\mathrm{(}}{x}{\mathrm{;}}{y}{\mathrm{);}}{A}{\mathrm{(}}{3}{\mathrm{;}}{2}{\mathrm{)}}\mathrm{\bigtriangleup}{\mathrm{;}}}\\
{\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\overrightarrow{n}{\mathrm{(}}{a}{\mathrm{;}}{b}{\mathrm{)}}\mathrm{{=}}{\mathrm{(}}{2}{\mathrm{;}}\mathrm{{-}}{1}{\mathrm{)}}\underline{\mathrm{|}}\mathrm{\bigtriangleup}}\\
{\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}{PTTQ}{\mathrm{:}}{a}{\mathrm{(}}{x}\mathrm{{-}}{x}_{oA}{\mathrm{)}}\mathrm{{+}}{b}{\mathrm{(}}{y}\mathrm{{-}}{y}_{oA}{\mathrm{)}}}\\
{\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\mathrm{\Leftrightarrow}{2}{x}\mathrm{{-}}{1}{y}\mathrm{{+}}{\mathrm{[}}\mathrm{{-}}{2}{\mathrm{.}}{3}\mathrm{{-}}{2}{\mathrm{(}}\mathrm{{-}}{1}{\mathrm{)}}{\mathrm{]}}}\\
{\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\hspace{0.33em}\mathrm{\Leftrightarrow}{2}{x}\mathrm{{-}}{1}{y}\mathrm{{-}}{4}\mathrm{{=}}{0}}
\end{array}
$
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