By using the Mawhin’s continuation theorem, this paper establishes a criterion for the existence of periodic orbits of the planar differential systems with delay angle. An example is provided to illustrate the application of the result.

中文翻译：

---

具有延迟角的平面微分系统周期轨道的存在

本文利用Mawhin延拓定理，建立了具有延迟角的平面微分系统周期轨道存在的判据。提供一个例子来说明结果的应用。