JEE Main & Advanced Mathematics Relations Question Bank Mock Test - Relations and Functions

  • question_answer
    The range of \[f(x)=co{{s}^{-1}}\left( \frac{1+{{x}^{2}}}{2x} \right)+\sqrt{2-{{x}^{2}}}\]is

    A) \[\left\{ 0,\,\,1+\frac{\pi }{2} \right\}\]     

    B) \[\left\{ 0,\,\,1+\pi  \right\}\]

    C) \[\left\{ 1,\,\,1+\frac{\pi }{2} \right\}\]     

    D) \[\left\{ 1,\,\,1+\pi  \right\}\]

    Correct Answer: C

    Solution :

    [c] \[{{\cos }^{-1}}\left( \frac{1+{{x}^{2}}}{2x} \right)\] is define if \[\left| \frac{1+{{x}^{2}}}{2x} \right|\le 1\] and \[x\ne 0\] or \[1+{{x}^{2}}-2\left| x \right|\le 0\] or \[{{(\left| x \right|-1)}^{2}}\le 0\] or \[x=1,-1\] Thus, the domain of \[f(x)\]is {1, -1}. Hence, the range is\[\{1,1+\pi \}\].


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