Help help 10 đ cho bài này:)

#include <bits/stdc++.h>
using namespace std;
double a,b,c,p,s;
int main()
{

    freopen("BAI2.INP","r",stdin);
    freopen("BAI2.OUT","w",stdout);
    cin>>a>>b>>c;
    p=(a+b+c)/2;
    s=p*(p-a)*(p-b)*(p-c);
    //cout<<"Chu vi tam giac la"<<a+b+c<<endl;
    cout<<fixed<<setprecision(2)<<sqrt(s);
}

\begin{array}{c} \color{#db1616}{\texttt{#Khoadang09}} \end{array}

#include <bits/stdc++.h>
using namespace std;
int main(){
    freopen("BAI2.INP","r",stdin);
    freopen("BAI2.OUT","w",stdout);
    double a, b, c; cin >> a >> b >> c;
    double p = (a+b+c)/2;
    double s = p*(p-a)*(p-b)*(p-c);
    cout << fixed << setprecision(2) << sqrt(s);
}