计算三角形面积

#include <iostream>

#include <cmath>

#include <iomanip>

using namespace std;

int main() 

{

float x1, y1, x2, y2, x3, y3;

double s,p,a,b,c;

cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;

a = sqrt(pow(x1 - x2, 2) + pow(y1 - y2, 2));

b = sqrt(pow(x1 - x3, 2) + pow(y1 - y3, 2));

c = sqrt(pow(x2 - x3, 2) + pow(y2 - y3, 2));

p = (a + b + c) / 2;

s = sqrt(p * (p - a) * (p - b) * (p - c));

cout << fixed << setprecision(2) << s << endl;

return 0;

}