On the Wallis Formula

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Bai-Ni Guo, Feng Qi, On the Wallis Formula, Int. J. Anal. Appl., 8 (1) (2015), 30-38.

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Bai-Ni Guo, Feng Qi

Abstract

By virtue of complex methods and tools, the authors express the famous Wallis formula as a sum involving binomial coefficients, establish the expansions for sink x and cosk x in terms of cos(mx), find the general formulas for the derivatives of sink x and cosk x, and recover the general multiple-angle formulas for sin(kx) and cos(kx), where k 2 N and m∈Z.

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