You can put this solution on YOUR website! sin^2x + cos^4x = cos^2x + sin^4x
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Rearrange to get::
cos^2(x)-sin^2(x) = cos^4(x)-sin^4(x)
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Divide both sides by cos^2(x) - sin^2(x) to get:
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1 = cos^2(x)+sin^2(x)
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1 = 1
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Cheers,
Stan H.