Phase plane methods to find limit cycle for non - linear dynamical systems

The phase plane method to findlimit cycle for  non - linear dynamical systems is considered one of the important studies specifically in the domain of  physics, engineering, economics, acquainted whether population of growth, administration and many of natural phenomenon so light is shed and this study aims to discuss a number of results concerning phase plane methods to find limit cycle in linear and non – linear dynamical systems, and to find fundamental review in phase plane methods, we followed the analytical induction mathematical methods , we found some the following results: The phase plane methods are graphical methods for  non – linear systems , and they are the  most general useful methods. and can find the limit cycle by graphical drawing.