JEE Main & Advanced Sample Paper JEE Main Sample Paper-7

  • question_answer
    If  \[(1+\tan \,{{1}^{o}})\,(1+\tan {{2}^{o}})\,(1+\tan {{3}^{o}})\] \[...(1+\tan {{45}^{o}})={{2}^{n}},\] then n equals

    A)  21                                         

    B)  22

    C)  23                                         

    D)  24

    Correct Answer: C

    Solution :

    If \[A+B={{45}^{o}}\] \[\Rightarrow \,\,(1+\tan A)\,(1+\tan B)=2\]. \[\therefore \] The given expression can be written as \[(1+\tan {{45}^{o}})\] \[\left\{ \begin{align}   & ((1+\tan {{1}^{o}})(1+\tan {{44}^{o}}))((1+\tan {{2}^{o}})(1+\tan {{43}^{o}})) \\  & ....(1+\tan {{22}^{o}})(1+\tan {{23}^{o}}) \\ \end{align} \right\}={{2}^{n}}\]\[\Rightarrow \,2\left[ {{2}^{22}} \right]={{2}^{n}}\] \[\Rightarrow \,n=23\]


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