How Do I Solve 1st and 2nd Derivative Homework Problems?

[LiHJ]

Homework Statement

Dear Mentors PF Helpers,

Here's my question:

I see it from my textbook with it solutions copied down below. Wonder is there another way to do it.
Thank you for your time.

Homework Equations

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The Attempt at a Solution

 

[ehild]

I do not see that you did any differentiation.

 

[LiHJ]

Sorry forgot to copied these as well

 

[ehild]

I do not see any other way than doing the differentiation. You may replace sec(x) by 1/cos(x), and replace the argument of the logarithm by (1+sinx)/cos(x) before differentiating.

 

[LiHJ]

Thank you