#include <iostream>
#include <cmath>
using namespace std;
int main()
{
double a, b, c, s, area, base, power=0.5;
cout << "輸入三角形ABC的邊長 a = ";
cin >> a;
cout << "輸入三角形ABC的邊長 b = ";
cin >> b;
cout << "輸入三角形ABC的邊長 c = ";
cin >> c;
s = (a + b + c) / 2;
// pow(base, power)
base = s * (s-a) * (s-b) * (s-c);
if (base < 0)
cout << "輸入的三邊長無法組成三角形! \n";
else
{
area = pow(base, power);
cout << "三角形ABC的面積 = " << area << endl;
}
system("pause");
return 0;
}