English
- #include <iostream>
- #include <cmath>
- using namespace std;
- int main()
- {double a,b,c,s,area;
- cout<<"please input a,b,c:";
- cin>>a>>b>>c;
- if (a+b<=c)
- cerr<<"a+b<=c,error!"<<endl;
- else if(b+c<=a)
- cerr<<"b+c<=a,error!"<<endl;
- else if (c+a<=b)
- cerr<<"c+a<=b,error!"<<endl;
- else
- {s=(a+b+c)/2;
- area=sqrt(s*(s-a)*(s-b)*(s-c));
- cout<<"area="<<area<<endl;}
- return 0;
- }
