Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-29

  • question_answer
    The value of \[\log \tan 1{}^\circ +\log \tan 2{}^\circ +\]\[.....+\log \tan 89{}^\circ \] is

    A)  0                    

    B)  1

    C)  \[\infty \]                      

    D)  None of these

    Correct Answer: A

    Solution :

    \[\log \tan 1{}^\circ +\log \tan 2{}^\circ +...+\log \tan 89{}^\circ \] \[=\]\[\log \,\,[\tan 1{}^\circ \cdot \tan 2{}^\circ ...\tan 45{}^\circ ...\tan 88{}^\circ \cdot \tan 89{}^\circ ]\] =\[\log \,\,[\tan 1{}^\circ \cdot \tan 2{}^\circ ...\tan 45{}^\circ ...\tan \] \[(90{}^\circ -2{}^\circ )\,\,\tan \,(90{}^\circ -1)]\] \[=\log \,\,[\tan 1{}^\circ \cdot cot1{}^\circ \cdot tan2{}^\circ \cdot cot2{}^\circ ...1]\] = log 1 = 0


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