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)
$