SOLUTION: prove: cos(3pi/4+x)cos(2pi+x)[cot(3pi/2-x)+cot(2pi+x)]=1

Question 815260: prove: cos(3pi/4+x)cos(2pi+x)[cot(3pi/2-x)+cot(2pi+x)]=1
Answer by Edwin McCravy(20059) (Show Source): You can put this solution on YOUR website!

Sorry, that is not an identity.

Put calculator in radian mode, let x=1 radian. Calculate:

Put it in your TI exactly this way:

cos(3p/4+1)cos(2p+1)(1/tan(3p/2-1)+1/tan(2p+1))

and you get -1.161134824, not 1.

There has to be a typo. 

Edwin

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