Inheritance

// rightTriangle.h

class rightTriangle : public triangle
{
   public:
	rightTriangle();
	rightTriangle(double side1, double side2);

        void setTriangle(double side1, double side2);

   private:
        double s1, s2;
};

// rightTriangle.C

rightTriangle::rightTriangle()
{
  s1 = 0; s2 = 0;
}

rightTriangle::rightTriangle(double side1, double side2)
{
  s1 = side1; s2 = side2;
}

void rightTriangle::setTriangle(double side1, double side2)
{
  s1 = side1; s2 = side2;
}


int rightTriangle::valid()
{
  if ( ( s1 >= 0 ) && ( s2 >= 0 ) )
    return TRUE;
  else
    return FALSE;
}


double triangle::angle1()
{
  if ( valid() )
    return atan( s2 / s1 );
  else
    return 0;
}

// ...

double rightTriangle::area()
{
  return s1 * s2 / 2.0;
}