text: #include "Line.h" //必须把自己放在放在第一行
  #include "Point.h" 
  #include <cmath>
  
  double Line::dis(const Point &lhs, const Point &rhs)
  {
  	double distance = sqrt((lhs.ix_ - rhs.ix_) * (lhs.ix_ - rhs.ix_)
  						   + (lhs.iy_ - rhs.iy_) * (lhs.iy_ - rhs.iy_)); 
  	return distance; 
  }
  