#include<iostream>
#include<cmath>
using namespace std;
class Triangle
{
  public:
        Triangle(double x,double y,double z)
        {
            a=x;
            b=y;
            c=z;
        }
        double isTriangle()
        {
            if(a+b>c&&a+c>b&&b+c>a)
                return true;
            else
                return false;
        }
        double getA()
        {
            return a;
        }
        double getB()
        {
            return b;
        }
        double getC()
        {
            return c;
        }
        double perimeter()
        {
            return a+b+c;
        }
        double area()
        {
           double t,w;
           w=(a+b+c)/2;
           t=w*(w-a)*(w-b)*(w-c);
           return sqrt(t);
        }
        double showMessage()
        {
            Triangle Tri(7,8,9);
            if(Tri.isTriangle())
        {
                cout <<"三条边为："<<Tri.getA()<<','<<Tri.getB()<<','<<Tri.getC()<<endl;
                cout << "三角形的周长为：" <<Tri.perimeter()<<'\t'<<"面积为："<<Tri.area()<< endl;
        }
            else
                cout<<"不能构成三角形"<<endl;

        }
    private:
        double a,b,c;
};

int main()
{
    Triangle Tri(7,8,9);
    Tri.showMessage();
    return 0;
}