#include <stdio.h> #include <math.h> #include using namespace std; int main() { double x1,x2,x3,y1,y2,y3; cin >>x1>> y1 >>x2>>y2>>x3>>y3; double a,b,c; a = sqrt( (x1 - x2)(x1 - x2) + (y1-y2)(y1-y2) ); b = sqrt( (x1 - x3)(x1 - x3) + (y1-y3)(y1-y3) ); c = sqrt( (x3 - x2)(x3 - x2) + (y3-y2)(y3-y2) ); double p = (a + b + c)/2; double s = sqrt( p * (p-a) * (p-b) * (p-c)); printf("%.2lf\n",s); }