#include <iostream.h>

#include <math.h> //for sqrt()

class C2D

{

protected:

double x, y; //x and y coordinates

public:

C2D() { x = y = 0.0; } //default constructor

C2D(double i, double j):x(i), y(j) { }

void setX(double newX) { x = newX; }

void setY(double newY) { y = newY; }

double getX() const { return x; }

double getY() const { return y; }

double getDistance(C2D point) const; // get distance of 2D points

};

// calculate the distance of two 2D points

double C2D::getDistance(C2D point) const

{

double dx, dy;

double distance;

dx = x – point.getX();

dy = y – point.getY();

distance = sqrt(dx * dx + dy * dy);

return distance;

}

class C3D:public C2D

{

private:

double z;

public:

C3D():C2D();

C3D(double i, double j, double k);

void setZ(double newZ);

double getZ();

double getDistance(C3D point) const; //get distance for two 3D points