What's the derivative of arctan(x/a)?

1 Answer
Aug 6, 2016

d/(dx)arctan(x/a)=a/(x^2+a^2)

Explanation:

y=arctan(x/a) is equivalent to tany=x/a

Now taking derivative of both sides

sec^2yxx(dy)/(dx)=1/a or

(dy)/(dx)=1/axx1/sec^2y

= 1/axx1/(1+tan^2y)

= 1/axx1/(1+x^2/a^2)

= 1/axxa^2/(x^2+a^2)

= a/(x^2+a^2)