SSC Sample Paper SSC CHSL (10+2) Sample Test Paper-7

  • question_answer
    If  \[0\,\underline{<}\,\theta \,\underline{<}\,\frac{\pi }{2}\]tan \[\theta =\frac{x}{y}\] then cos \[\theta \] =

    A)  \[\frac{\sqrt{{{x}^{2}}+{{y}^{2}}}}{y}\]                

    B)  \[\frac{\sqrt{{{x}^{2}}-{{y}^{2}}}}{y}\]

    C)  \[\frac{y}{\sqrt{{{x}^{2}}+{{y}^{2}}}}\]                

    D)  \[\frac{y}{\sqrt{{{x}^{2}}-{{y}^{2}}}}\]

    Correct Answer: C

    Solution :

     \[\tan \,\theta =\frac{x}{y}\]  \[{{\sec }^{2}}\theta =1+{{\tan }^{2}}\theta \] \[=1+\frac{{{x}^{2}}}{{{y}^{2}}}=\frac{{{y}^{2}}+{{x}^{2}}}{{{y}^{2}}}\] \[\Rightarrow \] \[\sec \theta =\frac{\sqrt{{{x}^{2}}+{{y}^{2}}}}{y}\] \[\therefore \]\[\cos \theta =\frac{1}{\sec \theta }=\frac{y}{\sqrt{{{x}^{2}}+{{y}^{2}}}}\]


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