Mathematics

Mathematics

Problem

Which of the following expressions is identically equal to 1 for every real value of xx? a) tan⁡2x+1\tan^2 x + 1 b) sin⁡2x−cos⁡2x\sin^2 x - \cos^2 x c) sin⁡2x+cos⁡2x\sin^2 x + \cos^2 x d) sin⁡x+cos⁡x\sin x + \cos x

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