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In this paper, a quadratic system with two parallel straight line-isoclinesis considered. This system corresponds to the system of class II in theclassification of Ye Yanqian. Using the field rotation parameters of theconstructed canonical system and geometric properties of the spirals fillingthe interior and exterior domains of its limit cycles, we prove that themaximum number of limit cycles in a quadratic system with two parallel straightline-isoclines and two finite singular points is equal to two. Besides, weobtain the same result in a different way: applying the Wintner-Perkotermination principle for multiple limit cycles and using the methods of globalbifurcation theory developed earlier by the author.

Limit Cycles of a Quadratic System with Two Parallel Straight Line-Isoclines