Find the derivative f (x) = ln CTG X / 2 at point x = - π / 6 It's minus one sixth of the point Find the derivative

Find the derivative f (x) = ln CTG X / 2 at point x = - π / 6 It's minus one sixth of the point Find the derivative

First of all, the derivative of F (x) = ln CTG X / 2 is obtained, where f (x) '= (LN CTG X / 2)' = (CTG X / 2) '/ (CTG X / 2) = 1 / 2 * (- 1-ctg ^ 2 x / 2) / (CTG X / 2) = - 1 / (2 SiNx / 2 * cosx / 2) = - 1 / SiNx is substituted into x = - π / 6, and f (- π / 6)' = 2 is obtained