SOLUTION: verify the identity step by step cot3x=1-tan^2x/3tanx-tan^3x

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Question 300647: verify the identity step by step
cot3x=1-tan^2x/3tanx-tan^3x

Answer by Edwin McCravy(20054)   (Show Source): You can put this solution on YOUR website!


Sorry, but that is not an identity, for let x = 45°







That's false, so it isn't an identity!

However, a correct identity, which is just like what you posted 
but has a -3 coefficient for the second factor in the top on the
right instead of -1 is given below, which makes me think this
is what it should have been:



















Multiply every term on top and bottom by LCD = 







Edwin
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