Alzer, Horst; Chu, Wenchang Two trigonometric identities. (English) Zbl 1307.26001 Ir. Math. Soc. Bull. 73, 21-28 (2014). MSC: 26A09 33B10 PDFBibTeX XMLCite \textit{H. Alzer} and \textit{W. Chu}, Ir. Math. Soc. Bull. 73, 21--28 (2014; Zbl 1307.26001) Full Text: Link
Gregorac, R. J. On Baica’s trigonometric identity. (English) Zbl 0675.42002 Int. J. Math. Math. Sci. 12, No. 1, 119-122 (1989). Reviewer: J.Jedrzejewski MSC: 42A05 41A50 PDFBibTeX XMLCite \textit{R. J. Gregorac}, Int. J. Math. Math. Sci. 12, No. 1, 119--122 (1989; Zbl 0675.42002) Full Text: DOI EuDML