#pragma once
class Triangle
{
protected:
    int _firstSide;
    int _secondSide;
    int _angle;
public:
    Triangle();
    Triangle(int first, int second, int ang);
    virtual double  countPerimetr();
    virtual double countArea();
};
class Equilateral : public Triangle
{
public:
    Equilateral(int first, int second, int ang);
    double countPerimetr() override;
    double countArea() override;
};
class Isosceles : public Triangle
{
public:
    Isosceles(int first, int second, int ang);
    double countPerimetr() override;
    double countArea() override;
};
class Rectangular : public Triangle
{
public:
    Rectangular(int first, int second, int ang);
    double countPerimetr() override;
    double countArea() override;
};
void setParameters(Triangle *&T);
============================
#include "Triangle.h"
#include <iostream>
#include <cmath>
using namespace std;


//произвольный треугольник
Triangle::Triangle()
{
}
Triangle::Triangle(int first, int second, int ang)
{
    _firstSide = first;
    _secondSide = second;
    _angle = ang;
}
double Triangle::countPerimetr()
{
    return sqrt(pow(_firstSide, 2) + pow(_secondSide, 2) - 2 * _firstSide * _secondSide * cos(_angle)) + _firstSide + _secondSide;
}
double Triangle::countArea()
{
    return (_firstSide * _secondSide * sin(_angle)) / 2;
}
//равносторонний треугольник
Equilateral::Equilateral(int first, int second, int ang)
{
    _firstSide = first;
    _secondSide = second;
    _angle = ang;
}
double Equilateral::countPerimetr()
{
    return _firstSide * 3;
}
double Equilateral::countArea()
{
    return (pow(_firstSide, 2) * sqrt(3)) / 4;
}
//равнобедренный треугольник
Isosceles::Isosceles(int first, int second, int ang)
{
    _firstSide = first;
    _secondSide = second;
    _angle = ang;
}
double Isosceles::countPerimetr()
{
    return sqrt(pow(_firstSide, 2) + pow(_secondSide, 2) - 2 * _firstSide * _secondSide * cos(_angle)) + _firstSide + _secondSide;
}
double Isosceles::countArea()
{
    return  (_firstSide * _secondSide * sin(_angle)) / 2;
}
//равносторонний треугольник
Rectangular::Rectangular(int first, int second, int ang)
{
    _firstSide = first;
    _secondSide = second;
    _angle = ang;
}
double Rectangular::countPerimetr()
{
    return sqrt(pow(_firstSide, 2) + pow(_secondSide, 2) - 2 * _firstSide * _secondSide * cos(_angle)) + _firstSide + _secondSide;
}
double Rectangular::countArea()
{
    return sqrt(pow(_firstSide, 2) + pow(_secondSide, 2)) + _firstSide + _secondSide;
}
void setParameters(Triangle *&T)
{
    int first, second, ang;
    cout << "Введите 1 сторону треугольника: \n";
    cin >> first;
    cout << "Введите 2 сторону треугольника: \n";
    cin >> second;
    cout << "Введите угол между сторонами треугольника: \n";
    cin >> ang;
    if (first <= 0 || second <= 0 || ang <= 0)
    {
        throw exception("Значения не могут быть меньше или равными 0!");
        exit(1);
    }
    if (T != NULL)
    {
        delete T;
    }
    if (first == second && ang == 60)
    {
        T = new Equilateral(first, second, ang);
    }
    else if (first == second && ang != 60)
    {
        T = new Isosceles(first, second, ang);
    }
    else if (ang == 90)
    {
        T = new Rectangular(first, second, ang);
    }
    else
        T = new Triangle(first, second, ang);
}
=========================
v#include <iostream>
#include "Triangle.h"
using namespace std;

int main()
{
    setlocale(0, "Rus");
    try
    {
        Triangle *T = NULL;
        setParameters(T);
        cout << "Площадь треугольника: " << T->countArea() << endl;
        cout << "Периметр треугольника: " << T->countPerimetr() << endl;
    }
    catch (const exception& ex)
    {
        cout << ex.what() << endl;
    }
}