TIJIE

#include <bits/stdc++.h>
using namespace std;
int main()
{
    double a,b,c,p;
    cin>>a>>b>>c;
    p=(a+b+c)/2;
    cout<<fixed<<setprecision(2)<<sqrt(p*(p-a)*(p-b)*(p-c));
}

| 1 | 4 |
|--2-|--5-|
| 3 | 6 |