The sum-to-product formula is given by:
$$\sin a - \sin b = 2 \cos \left(\frac{a+b}{2}\right) \sin \left(\frac{a-b}{2}\right)$$
Applying this to our equation, we get:
$$\sin 5x - \sin x = 2 \cos \left(\frac{5x+x}{2}\right) \sin \left(\frac{5x-x}{2}\right) = 2 \cos
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