$\int {\left( {\dfrac{1}{{{{\sin }^2}x}} + \dfrac{1}{{{{\cos }^2}x}}} \right)dx}  = \tan x - \cot x + C$       

$\int {\left( {\dfrac{1}{{{{\sin }^2}x}} + \dfrac{1}{{{{\cos }^2}x}}} \right)dx}  = \cot x - \tan x + C$

$\int {\left( {\dfrac{1}{{{{\sin }^2}x}} + \dfrac{1}{{{{\cos }^2}x}}} \right)dx}  = \cot x + \tan x + C$      

$\int {\left( {\dfrac{1}{{{{\sin }^2}x}} + \dfrac{1}{{{{\cos }^2}x}}} \right)dx}  =  - \cot x - \tan x + C$