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Why is [math]\cos\alpha \cos\beta=\frac{1}{2}[\cos(\alpha-\beta)+\cos(\alpha+\beta)][/math]?
Can you explain why [math]\cos\alpha \cos\beta=\frac{1}{2}[\cos(\alpha-\beta)+\cos(\alpha+\beta)][/math]?
Certainly! By using the product-to-sum identities, we can rewrite [math]\cos\alpha \cos\beta[/math] as [math]\frac{1}{2}[\cos(\alpha+\beta)+\cos(\alpha-\beta)][/math].