Question 815260
<pre>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(3<font face="symbol">p</font>/4+1)cos(2<font face="symbol">p</font>+1)(1/tan(3<font face="symbol">p</font>/2-1)+1/tan(2<font face="symbol">p</font>+1))

and you get -1.161134824, not 1.

There has to be a typo. 

Edwin</pre>