11. The content of the chapters ``Lines in the Coordinate Plane'' and ``Conic Sections'' in the textbook embodies that the essence of analytic geometry is $\_\_\_\_$ $\_\_\_\_$.
11. The content of the chapters ``Lines in the Coordinate Plane'' and ``Conic Sections'' in the textbook embodies that the essence of analytic geometry is $\_\_\_\_$\\
$\_\_\_\_$.\\