Why Does the Derivative of 2 + tan(x/2) Include a .5 Term?

bobsmith76
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Homework Statement



Screenshot2012-02-03at51057AM.png


Screenshot2012-02-03at51050AM.png



I understand everything except why the derivative of 2 + tan (x/2) is .5 + sec^2(x/2)
I don't understand the .5 part. I understand the sec part. I would think the derivative of 2 would be C, or just disappear.
 
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never mind. I got it. I've got to use the chain rule. the derivative of t/2 is 1/2
 
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