SOLUTION: cos^4a+cos^2a=1 ,prove is it identity or not,thanks and regards

SOLUTION: cos^4a+cos^2a=1 ,prove is it identity or not,thanks and regards

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Question 766371: cos^4a+cos^2a=1 ,prove is it identity or not,thanks and regards
Answer by tommyt3rd(5050) (Show Source): You can put this solution on YOUR website!
not an identity:
To disprove an identity we need only a single exception:

and not 1

:)
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