Use sum-to-product identities to rewrite the expression as a product. \( \sin 7 x+\sin 3 x \) \( 2 \cos 5 x \sin 2 x \) \( 2 \sin 10 x \) \( 2 \sin 5 x \sin 2 x \) \( 2 \sin 5 x \cos 2 x \) QUESTION 1