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Sec^4x-tan^4x=sec^2x+tan^2x

User Sonaryr
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1 Answer

1 vote

\sec^4x-\tan^4x=(\sec^2x-\tan^2)(\sec^2x+\tan^2x)=\sec^2x+\tan^2x

since
\tan^2x+1=\sec^2x.
User Pitaridis
by
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