#include<iostream.h>
#include <math.h>
class tria
{
public:
    void setsides(float a,float b,float c);
    void print();
private:
    float x,y,z;
    float area;
};
void main()
{
    tria tr1;
    tr1.setsides(3,4,5);
        tr1.print();
}
void tria::setsides(float a,float b,float c)
    {
        if (a+b>c&&a+c>b&&b+c>a)
        {
            x=a;y=b;z=c;
            float t=(a+b+c)/2;
            area=sqrt(t*(t-a)*(t-b)*(t-c));
        }
        else
            x=y=z=area=0;
    }
void tria::print()
    {
        cout<<"三角形的三条边长分别是："<<endl;
        cout<<x<<"\t"<<y<<"\t"<<z<<endl;
        cout<<"三角形面积为："<<endl;
        cout<<area<<endl;   
    }