设计一个三角形类（多文件）

#ifndef _TRIANGLE_
#define _TRIANGLE_
class Triangle {
private:
	double a, b, c;
public:
	Triangle();
	Triangle(double a, double b, double c);
	Triangle(Triangle &t);
	double getL();
	double getS();
	~Triangle();
};
#endif

#include"Triangle.h"
#include<cmath>
Triangle::~Triangle(){}
Triangle::Triangle()
{
}
Triangle::Triangle(double a, double b, double c)
{
	this->a = a;
	this->b = b;
	this->c = c;
} 
Triangle::Triangle(Triangle &t)
{
	a = t.a;
	b = t.b;
	c = t.c;
}
double Triangle::getL()
{
	return a + b + c;
}
double Triangle::getS()
{
	double p = (a + b + c) / 2;
	return sqrt(p*(p - a)*(p - b)*(p - c));
}

#include"Triangle.h"
#include<iostream>
using namespace std;
int main()
{
	Triangle t1;
	Triangle t2(6,8,10);
	Triangle t3(t2);
	cout << t2.getL() << endl;
	cout << t3.getS ()<< endl;
	system("pause");
	return 0;
}