3 4 5
6.0000
1 #include<iostream> 2 #include<cstdio> 3 #include<cmath> 4 using namespace std; 5 int main() 6 { 7 double a,b,c; 8 cin>>a>>b>>c; 9 double p=(a+b+c)/2; 10 printf("%.4lf",sqrt(p*(p-a)*(p-b)*(p-c))); 11 return 0; 12 }