T1 - zad.2.

#include <iostream>
#include <cmath>

int main()
{
    double a, b, c;
    std:: cout << "Unesite tri broja: ";


   for(;;)
    {
        std:: cin >> a >> b >> c;
        if(std:: cin) break;
        std:: cout<<"Niste unijeli ispravno stranice!"<<std:: endl;
        std:: cin.clear();
        std:: cin.ignore(10000,'\n');
        std:: cout << "Unesite tri broja: ";
     }

    while ((a<0)||(b<0)||(c<0))
    {
        std:: cout<<"Niste unijeli ispravno stranice!"<< std:: endl;
        std:: cin.clear();
        std:: cin.ignore(10000,'\n');
        std:: cout << "Unesite tri broja: ";
        std:: cin >> a >> b >> c;
}

    if((a+b)>c && (a+c)>b && (b+c)>a)
        {
            double s;
            s=(a+b+c)/2;
            std:: cout << "Povrsina trougla sa duzinama stranica "
                       <<a<< ", "<<b<<" i "<<c<< " iznosi "
                       <<sqrt(s*(s-a)*(s-b)*(s-c))<< std:: endl;

            double alfa, beta, gama;

            gama=acos((a*a+b*b-c*c)/(a*b*2));
            alfa=acos((c*c+b*b-a*a)/(c*b*2));
            beta=acos((a*a+c*c-b*b)/(a*c*2));

            double maxi=0;
            if (alfa>maxi) maxi=alfa;
            if (beta>maxi) maxi=beta;
            if (gama>maxi) maxi=gama;

            double ugao;
            ugao=maxi*(180/(4*atan(1)));

            int m,sec;
            m=(ugao-int(ugao))*60;
            sec=(ugao-int(ugao) - m/60.0)*3600;


            std:: cout<< "Najveci ugao zadanog trougla iznosi: "
                      <<int(ugao) <<" stepeni, "
                      <<int(m) << " minuta i "
                      <<int(sec) <<" sekundi."<< std:: endl;
         }
    else
      std:: cout << "Ne postoji trougao cije su duzine stranica "
                <<a<< ", "<<b<<" i "<<c;


    return 0;
}