SOLUTION: write each expression as a sum or difference of trigonometric functions. 8 sin 7x sin 9x thanks!

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Question 846447: write each expression as a sum or difference of trigonometric functions.
8 sin 7x sin 9x
thanks!
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
write each expression as a sum or difference of trigonometric functions.
8 sin 7x sin 9x
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Formula: 2sin(A)sin(B) = [cos(A-B)-cos(A+B)]
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Your Problem:
4[2sin(7x)sin(9x)] = 4[cos(2x)-cos(16x)]
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Cheers,
Stan H.
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