Let the function k is defined as $k(\alpha) = \cos(2\alpha)$. Which of these is an equivalent expression for $k(\alpha)$? $\cos^2 \alpha - \sin^2 \alpha$ $\cos^2 \alpha + \sin^2 \alpha$ 1 $\cos^2 \alpha \cdot \sin^2 \alpha$
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Step 1
This involves recalling the double angle identities for cosine. Step 2: Recall the double angle identities for cosine. There are three common forms for $\cos(2\alpha)$: 1. $\cos(2\alpha) = \cos^2 \alpha - \sin^2 \alpha$ 2. $\cos(2\alpha) = 2\cos^2 \alpha - 1$ 3. Show more…
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