Which of the following is an exact expression for ?

MATHEMATICS · Single correct · A Level · Mathematics · Trigonometry · Trigonometry

Problem

Which of the following is an exact expression for cos⁡2θ\cos 2\theta? (a) 1−2sin⁡θ1-2\sin\theta (b) 2sin⁡θcos⁡θ2\sin\theta\cos\theta (c) cos⁡2θ−sin⁡2θ\cos^{2}\theta-\sin^{2}\theta (d) 2sin⁡2θ−12\sin^{2}\theta-1

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