29.1

#include <iostream>
#include <cmath>

using namespace std;

int main() {
    float x1, y1, x2, y2, x3, y3;

    cout << "Tochka 1 (x y): "; cin >> x1 >> y1;
    cout << "Tochka 2 (x y): "; cin >> x2 >> y2;
    cout << "Tochka 3 (x y): "; cin >> x3 >> y3;

    float a = sqrt((x2 - x3) * (x2 - x3) + (y2 - y3) * (y2 - y3));
    float b = sqrt((x1 - x3) * (x1 - x3) + (y1 - y3) * (y1 - y3));
    float c = sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));

    if (a + b > c && a + c > b && b + c > a) {
        float P = a + b + c;
        float p = P / 2;
        float S = sqrt(p * (p - a) * (p - b) * (p - c));

        cout << "Perimetur: " << P << endl;
        cout << "Lice: " << S << endl;
    } else {
        cout << "Ne moje da ima triugulnik!" << endl;
    }

    return 0;
}