BB':x-2y+1=0CC':3x+y-1=0A$\epsilon$ABvà CC' vuông góc vs AB$\Rightarrow$AB:x-3y-1=0Tương tự AC:2x+y-2=0$\Rightarrow$B(-5;-2);C(-1;4)$\Rightarrow$S$\triangle $ABC=1/2.d(B,AC).AC=14(đvdt)
$BB':x-2y+1=0$$CC':3x+y-1=0$A$\epsilon$ABvà CC' vuông góc vs AB$\Rightarrow$$AB:x-3y-1=0$Tương tự $AC:2x+y-2=0$$\Rightarrow B(-5;-2);C(-1;4)$$\Rightarrow$S$\triangle $$ABC=1/2.d(B,AC).AC=14(đvdt)$