php, 269 bytes

Result

WA

Duration

480ms

Code [DL]

<?php[$a,$b,$c]=explode(" ",fgets(STDIN));[$d,$e,$f]=explode(" ",fgets(STDIN));[$g,$h,$i]=explode(" ",fgets(STDIN));[$j,$k,$l]=explode(" ",fgets(STDIN));$g-=$a;$h-=$b;$i-=$c;$j-=$a;$k-=$b;$l-=$c;echo(($e-$b)*($i*$j-$g*$l)+($f-$c)*($g*$k-$h*$j)+($d-$a)*($h*$l-$i*$k))/6;

stdin

47 54 33
45 35 93
83 30 41
48 86 02

stdout

<?php[$a,$b,$c]=explode(" ",fgets(STDIN));[$d,$e,$f]=explode(" ",fgets(STDIN));[$g,$h,$i]=explode(" ",fgets(STDIN));[$j,$k,$l]=explode(" ",fgets(STDIN));$g-=$a;$h-=$b;$i-=$c;$j-=$a;$k-=$b;$l-=$c;echo(($e-$b)*($i*$j-$g*$l)+($f-$c)*($g*$k-$h*$j)+($d-$a)*($h*$l-$i*$k))/6;

stderr

strace