JEE Main & Advanced JEE Main Paper (Held On 25 April 2013)

  • question_answer
                    Let \[x\]\[\in \](0, 1). The set of all \[x\] such that\[\text{si}{{\text{n}}^{-\text{1}}}x>{{\cos }^{-1}}x,\] is the interval :     JEE Main Online Paper ( Held On 25  April 2013 )

    A)                 \[\left( \frac{1}{2},\frac{1}{\sqrt{2}} \right)\]                     

    B)                                        \[\left( \frac{1}{\sqrt{2}},1 \right)\]

    C)                                        \[\left( 0,1 \right)\]                        

    D)                                        \[\left( 0,\frac{\sqrt{3}}{2} \right)\]

    Correct Answer: B

    Solution :

                     Given \[{{\sin }^{-1}}x>{{\cos }^{-1}}x\]where \[x\in (0,1)\] \[\Rightarrow \]\[{{\sin }^{-1}}x>\frac{\pi }{2}-{{\sin }^{-1}}x\]\[\Rightarrow \]\[2{{\sin }^{-1}}x>\frac{\pi }{2}\] \[\Rightarrow \]\[{{\sin }^{-1}}x>\frac{\pi }{4}\]\[\Rightarrow \]\[x>\sin \frac{\pi }{4}\Rightarrow x>\frac{1}{\sqrt{2}}\] Maximum value of \[{{\sin }^{-1}}x\] is\[\frac{\pi }{2}\] So, maximum value of x is 1. So,\[x\in \left( \frac{1}{\sqrt{2}},1 \right).\]


You need to login to perform this action.
You will be redirected in 3 sec spinner