_>#include <math.h>

_>struct tetrahedron {
_>    double a,b,c,ea,eb,ec;
_>    double volume() const {
_>        double A=a*a, B=b*b, C=c*c, X=B+C-ea*ea, Y=A+C-eb*eb, Z=A+B-ec*ec;
_>        return sqrt(4*A*B*C-A*X*X-B*Y*Y-C*Z*Z+X*Y*Z)/12;
_>    }
_>};

_>#include <stdio.h>

_>int main(int argc,char** argv) {
_>    tetrahedron t;
_>    t.a=1;  t.b=1;  t.c=1;
_>    t.ea=1; t.eb=1; t.ec=1;
_>    double V=t.volume(), V0=sqrt(2)/12;
_>    printf("V=%.5f (%.5f)\n",V,V0);
_>    return 0;
_>}
_>