Which of the following identities is always true for any acute angle ?

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

Problem

Which of the following identities is always true for any acute angle θ\theta? (a) sin⁡θ+cos⁡θ=1\sin\theta+\cos\theta=1 (b) sin⁡2θ+cos⁡2θ=1\sin^2\theta+\cos^2\theta=1 (c) tan⁡2θ+1=cot⁡2θ\tan^2\theta+1=\cot^2\theta (d) sec⁡θ−tan⁡θ=1\sec\theta-\tan\theta=1

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