JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2008

  • question_answer
        If\[a>b>0,\]then the value of\[{{\tan }^{-1}}\left( \frac{a}{b} \right)+{{\tan }^{-1}}\left( \frac{a+b}{a-b} \right)\]depends on

    A)  both a and b     

    B)  band not a

    C)  a and not b       

    D)  neither a nor b

    Correct Answer: D

    Solution :

                    \[{{\tan }^{-1}}\left( \frac{a}{b} \right)+{{\tan }^{-1}}\left( \frac{a+b}{a-b} \right)\] \[={{\tan }^{-1}}\left( \frac{\frac{a}{b}+\frac{a+b}{a-b}}{1-\frac{a}{b}\left( \frac{a+b}{a-b} \right)} \right)\] \[={{\tan }^{-1}}\left( \frac{{{a}^{2}}-ab+ab+{{b}^{2}}}{ab-{{b}^{2}}-{{a}^{2}}-ab} \right)\] \[={{\tan }^{-1}}\left( -\frac{{{a}^{2}}+{{b}^{2}}}{{{a}^{2}}+{{b}^{2}}} \right)={{\tan }^{-1}}(-1)\] \[\therefore \]The value is neither depends on a nor b.


You need to login to perform this action.
You will be redirected in 3 sec spinner