Goi A(a;12-2a); B(b;b-2); C(5c-3;c)
=>$\overrightarrow{BC}(5c-b-3;c-b+2)$ vuong goc vs $\overrightarrow{AH}$
$=>5c-b-3=2(c-b+2)=>b=7-3c ( _1)$
ta co trung diem M cua AB toa do la $M(\frac{a+b}2;\frac{10-2a+b}2)\in CM$
$=>b=a\frac{11}4-11=7-3c$
$=>\overrightarrow{BA}_{(-b\frac7{11}+4;-b\frac{19}{11}+6)}+\overrightarrow{BC}_{(\frac{8b-26}{3};\frac{4b-13}{3})}=k.\overrightarrow{BD}_{(1;-1)}$
$=>-b\frac7{11}+4+\frac{8b-28}3=-(-b\frac{19}{11}+6+\frac{4b-13}3)\Leftrightarrow b=\frac{-121}{54}=>a;c=..........$