三角形面积.cpp

给各个边长

#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;
int main()
{
	double a,b,c;
	cout<<"please enter a,b,c:";
	cin>>a>>b>>c;
	if (a+b>c&&b+c>a&&a+c>b)
	{
		double s,area;
		s=(a+b+c)/2;
		area=sqrt(s*(s-a)*(s-b)*(s-c));
		cout<<setiosflags(ios::fixed)<<setprecision(4);
		cout<<"area="<<area<<endl;
	}
	else cout<<"it is not a rilateral!"<<endl;
	return 0;
}