substitute tanx=z^2, then u will get dx=2zdz/(1+z^2).. then put tanx=z and the value of dx in the given integral.. i hope u can do after that urself. good luck!
Niladri Chakraborty, you're wrong...
You should be sure before you post an answer...
The question now becomes
Writing 2t2 as (1+t2) - (1-t2), we get 2 integrals.
Divide numerator and denominator by t2 in both the integrals to get the 2 integrals as
In first integral, put t - 1/t = u
In second integral, put t + 1/t = v
Integrate....hope you can do the rest.........