Класс "Треугольник"

#ifndef TRIANGLE_H
#define TRIANGLE_H
 
class Triangle {
public:
    Triangle();
    Triangle(double a, double b, double c);
    virtual ~Triangle();
    
    bool isValid();
    void height();
private:
    double a, b, c, h;
    friend void printTriangle(Triangle &tri);
   
};
 
#endif /* TRIANGLE_H */

#include "Triangle.h"
#include <iostream>
 
using namespace std;
 
Triangle::Triangle() 
{
}
 
Triangle::Triangle(double a, double b, double c)
: a(a), b(b), c(c)
{
}
 
Triangle::~Triangle()
{
}
 
bool Triangle::isValid()
{
    if ((a>0)&(b>0)&(c>0)) 
        cout << " The coord is negative";
}
 
void Triangle::height()
{
    h = (a*b) / c;
}
 
void printTriangle(Triangle &tri)
{
    cout << "h=" << tri.h << " a=" << tri.a << " b=" << tri.b << " c=" << tri.c << endl;
}

#include <cstdlib>
#include<iostream>
#include"Triangle.h"
 
using namespace std;
 
void playCase(Triangle *tri1, Triangle *tri2)
{
    cout << "Triangle 1: ";
    printTriangle(*tri1);
    cout << "Triangle 2: ";
    printTriangle(*tri2);
}
int main(int argc, char** argv) {
    
    
    Triangle *tri1 = new Triangle(3, 4, 5);
    Triangle *tri2 = new Triangle(3, -4, 5);
    cout << "Case 1:" << endl;
    playCase(tri1, tri2);
    cout << endl;
    return 0;
}