Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-2

  • question_answer
    If \[\sec \,\alpha \,=\,\frac{5}{4},\] then \[\frac{\tan \alpha }{1+{{\tan }^{2}}\alpha }\] is equal to

    A)  \[\frac{9}{25}\]            

    B)  \[\frac{12}{25}\]

    C)  \[\frac{3}{4}\]

    D)  \[\frac{1}{25}\]

    Correct Answer: B

    Solution :

    \[\because \] \[\sec \alpha =\frac{5}{4}\]. \[\therefore \]\[\tan \alpha =\sqrt{{{\sec }^{2}}\alpha -1}\] \[\therefore \]\[=\sqrt{\frac{25}{16}-1}=\sqrt{\frac{25-16}{16}}=\sqrt{\frac{9}{16}}=\frac{3}{4}\] Now, \[\frac{\tan \alpha }{1+{{\tan }^{2}}\alpha }=\frac{3/4}{1+{{(3/4)}^{2}}}=\frac{3/4}{1+9/16}\] \[=\frac{3/4}{25/16}=\frac{12}{25}\]


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