# Trigonometric integrals

1. Feb 3, 2012

### bobsmith76

1. The problem statement, all variables and given/known data

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.

2. Feb 3, 2012

### bobsmith76

never mind. I got it. i've got to use the chain rule. the derivative of t/2 is 1/2