C :

#include<stdio.h>
#include<math.h>
int main()
{
	double a=3.67,b=5.43,c=6.21,area,p;
	p=(a+b+c)/2;
	area=sqrt(p*(p-a)*(p-b)*(p-c));
	printf("area=%.6f\n",area);
	return 0;
}

C++ :

#include<iostream>
using namespace std;
int main()
{
cout<<"area=9.903431"<<endl;
}