Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-31

  • question_answer
    If t\[\tan \theta =\frac{1}{\sqrt{7}}\]then\[\frac{\cos e{{c}^{2}}\theta -{{\sec }^{2}}\theta }{\cos e{{c}^{2}}\theta +{{\sec }^{2}}\theta }\]equal to

    A)  \[\frac{-3}{4}\]            

    B)  \[\frac{-2}{3}\]

    C)  \[\frac{2}{3}\] 

    D)  \[\frac{3}{4}\]

    Correct Answer: D

    Solution :

    Given, \[\tan \theta =1\] \[AC=\sqrt{A{{B}^{2}}+C{{B}^{2}}}\] \[=\sqrt{1+7}=2\sqrt{2}\] Then,  \[\frac{\text{cose}{{\text{c}}^{2}}\theta -{{\sec }^{2}}\theta }{\text{cose}{{\text{c}}^{2}}\theta +{{\sec }^{2}}\theta }\]                                   ?(i)     From \[\Delta ABC,\] \[\text{cosec}\theta =\frac{2\sqrt{2}}{1}\] and       \[\sec \theta =\frac{2\sqrt{2}}{\sqrt{7}}\] Put the value of \[\sec \theta \] and\[\text{cosec}\theta \] in Eq. (i) \[\Rightarrow \]\[\frac{{{(2\sqrt{2})}^{2}}-{{\left( \frac{2\sqrt{2}}{\sqrt{7}} \right)}^{2}}}{{{(2\sqrt{2})}^{2}}+{{\left( \frac{2\sqrt{2}}{7} \right)}^{2}}}=\frac{8-\frac{8}{7}}{8+\frac{8}{7}}\] \[=\frac{56-8}{56+8}=\frac{48}{64}=\frac{3}{4}\]


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