1011 卫生包干区的面积

#include<iostream>#include<iomanip>#include<math.h>using namespace std;#define pi 3.14int main(){double a,b,c,p,s;cin>>a>>b>>c;p=(a+b+c)/2;s=sqrt(p*(p-a)*(p-b)*(p-c));cout<<setiosflags(ios::fixed)<<setprecision(2)<<s<<endl;return 0;}