C :

#include<stdio.h>
#include<math.h>
#include<string.h>
double S(double b1,double b2,double b3,double b4,double b5,double b6,double b7)
{
	double cos1,cos2,cos3,sin1,sin2,sin3,s1,s2,s3;
	  cos1=(b5*b5*1.0+b6*b6*1.0-b1*b1*1.0)/(2.0*b5*b6);
	sin1=sqrt(1.0-cos1*cos1*1.0);
	s1=0.5*b5*b6*sin1;
	  cos2=(b6*b6*1.0+b7*b7*1.0-b2*b2*1.0)/(2.0*b7*b6);
	sin2=sqrt(1.0-cos2*cos2*1.0);
	s2=0.5*b7*b6*sin2;
	  cos3=(b7*b7*1.0+b4*b4*1.0-b3*b3*1.0)/(2.0*b7*b4);
	sin3=sqrt(1.0-cos3*cos3*1.0);
	s3=0.5*b4*b7*sin3;
	return s1+s2+s3;
} 



int main()
{
	double a,s,d,f,g,h,j;
	scanf("%lf%lf%lf%lf%lf%lf%lf",&a,&s,&d,&f,&g,&h,&j);
	printf("%.3lf",S(a,s,d,f,g,h,j));
		return 0;
}

C++ :

	#include<iostream>
	#include<cstdio> 
	#include<cmath>                 
	using namespace std;
	double area(double a,double b,double c)
	{
	    double p=(a+b+c)/2;
	    return sqrt(p*(p-a)*(p-b)*(p-c));
	}
	int main()
	{
	    double b1,b2,b3,b4,b5,b6,b7,s;
	    //cout<<"please input b1,b2,b3,b4,b5,b6,b7:"<<endl;
	    cin>>b1>>b2>>b3>>b4>>b5>>b6>>b7;//调用三次函数area
	    s=area(b1,b5,b6)+area(b2,b6,b7)+area(b3,b4,b7);  
	    printf("%0.3lf\n",s);
	    return 0;
 	}