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Question
Express the following as the product of sine and cosine.
sin 6θ – sin 2θ
Solution
sin 6θ – sin 2θ
`= 2 cos ((6theta + 2theta)/2) cos ((6theta - 2theta)/2)` ...`[∵ sin "C" - sin "D" = 2 cos (("C + D")/2) cos (("C - D")/2)]`
= 2 cos `((8theta)/2) sin ((4theta)/2)`
= 2 cos 4θ sin 2θ
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