Which of the following expressions is identically equal to 1 for every real angle ?

MATHEMATICS · Single correct · CBSE · Mathematics · Introduction to Trigonometry · Introduction to Trigonometry

Problem

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

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