Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-10

  • question_answer
    If \[\tan \alpha =\frac{m}{m+1}\] and \[\tan \beta =\frac{1}{2m+{{1}^{'}}}\] then \[\alpha +\beta \]is equal to

    A)  \[\frac{\pi }{3}\]                       

    B)  \[\frac{\pi }{4}\]

    C)  \[\frac{\pi }{6}\]           

    D)  \[\frac{3\pi }{2}\]

    Correct Answer: B

    Solution :

    \[\tan (\alpha +\beta )=\frac{\tan \alpha +\tan \beta }{1-\tan \alpha .\tan \beta }\] \[\,=\frac{\frac{m}{m+1}+\frac{1}{2\,\,m+1}}{1-\left( \frac{m}{m+1} \right)\left( \frac{1}{2\,\,m+1} \right)}\] \[=\frac{2{{m}^{2}}m+m+1}{2{{m}^{2}}+2m+m+1-m}\] \[\,=\frac{2{{m}^{2}}+2m+1}{2{{m}^{2}}+2m+1}=1\] \[\therefore \,\] \[\alpha +\beta ={{\tan }^{-1}}(1)=\pi /4\]


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