Task29

class Task29 {
    public static double calcQuadrilateralSquare(double x, double y, double z, double t) {
        double ans = 0;
        ans += x*y/2;
        double c = Math.sqrt(x*x+y*y);
        double p = (z+t+c)/2;
        ans += Math.sqrt(p*(p-c)*(p-z)*(p-t));
        return ans;
    }
}