Use a power-reducing identity to rewrite the following expression below in terms containing only first powers of cosine. Help?

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1 Answer
sankarankalyanam
Mar 7, 2018

#=> color(purple)( (1-cos 4x) / 8#

Explanation:

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#cos^4x tan^2x =(cancel cos^2x * cos ^2x) (sin^2 x / cancel(cos^2x))#

#=> cos^2x sin^2 x = (cos x sin x)^2 = ((sin 2x) / 2)^2#

#=> (1/4) sin^2 2x = (1/4) * (1 - cos4x)/2 =color(purple)( (1-cos 4x) / 8#

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