More Differentiation help needed please!?

Question

Differentiate the following function of x (using either the product, quotient or chain rule)

f(x) = ln(secx + tanx)

Thanks in advance :) 10pts to first correct answer with clear working

Answer 1

Chain rule and you need to know these:

(ln f(x))' = f'(x)/f(x)

(secx)' = secx tanx

(tanx)'=sec^2 x

so ln(secx + tanx)'

= (secx tanx + sec^2 x)/(secx + tanx)

= secx