#include <iostream> #include<iomanip> #include<cmath> using namespace std; int main() { int a,b,c; cin>>a>>b>>c; float circumference,area; circumference=a+b+c; float s=circumference/2; area=sqrt(s*(s-a)*(s-b)*(s-c)); cout<<fixed<<setprecision(2);//输出保留...