What is the derivative of \({\tan ^{ - 1}}\left( {\frac{{\sqrt {1{\rm{\;}} + {{\rm{x}}^2}} - {\rm{\;}}1}}{{\rm{x}}}} \right)\) with respect to tan-1 x ?

What is the derivative of \({\tan ^{ - 1}}\left( {\frac{{\sqrt {1{\rm{

1.	What is the derivative of \({\tan ^{ - 1}}\left( {\frac{{\sqrt {1{\rm{\;}} + {{\rm{x}}^2}} - {\rm{\;}}1}}{{\rm{x}}}} \right)\) with respect to tan-1 x ?
A.	0
B.	½
C.	1
D.	x
Answer» C. 1