Question 1067701
Can somebody help me by writing 4 cos 2θ sin 4θ as a sum or difference? 
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a+b = 40
a-b = 20
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2a = 60
a = 30
Then b = 10
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4[cos(20)*sin(40)] = 4[cos(20-40)+cos(20+40)]
= 4[cos(20)+cos(60)]
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Cheers,
Stan H.
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