This is the peer reviewed version of the following article: Diaz-Barrero, J.L. A cyclic trigonometric inequality. "School science and mathematics [en li­nia]", Octubre 2018, vol. 118, num. 6, p. 271, which has been published in final form at https://onlinelibrary.wiley.com/doi/abs/10.1111/ssm.12296. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

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这是以下文章的同行评审版本：Diaz-Barrero, JL 循环三角不等式。“学校科学与数学 [en linia]”，Octubre 2018，第一卷。118，编号。6，第。271，已在 https://onlinelibrary.wiley.com/doi/abs/10.1111/ssm.12296 上以最终形式发布。根据 Wiley 自我存档条款和条件，本文可用于非商业目的。