#include <iostream>
#include <cmath>   
#include "point.h"
using namespace std;

point::point(double initial_r, double initial_theta)
    : r {initial_r}, theta {initial_theta} 
{
}

point::point()
    : r {0}, theta {0}  
{
}

double point::r() const   
{
    return r; 
}

double point::theta() const  
{
    return theta;  
}

void point::print() const
{
    cout << "(r = " << r << ", theta = " << theta << ")";  
}

double point::x() const
{
    return r * cos(theta);
}

double point::y() const
{
    return r * sin(theta);  
}

double distance(const point& A, const point& B)
{
    const double dx = A.x() - B.x(); 
    const double dy = A.y() - B.y();
    return sqrt(dx * dx + dy * dy);
}

double area(const point& A, const point& B, const point& C)
{
    return abs(A.x() * (B.y() - C.y()) +
               B.x() * (C.y() - A.y()) +
               C.x() * (A.y() - B.y())) / 2.0;
}