JEE Main & Advanced Sample Paper JEE Main Sample Paper-33

  • question_answer
    The number of ordered triplets (x, y, z) of real numbers that satisfy the equation \[{{({{\sin }^{-1}}x)}^{2}}=\frac{{{\pi }^{2}}}{4}+{{({{\sec }^{-1}}y)}^{2}}+{{({{\tan }^{-1}}z)}^{2}}\]is

    A)  2              

    B)                    4

    C)  6            

    D)                                     8

    Correct Answer: A

    Solution :

    \[({{\sin }^{-1}}x)\in \,\left[ \frac{-\pi }{2},\,\frac{\pi }{2} \right]\]             \[\therefore \,\,\,{{({{\sin }^{-1}}x)}^{2}}\,\le \frac{{{\pi }^{2}}}{4}\,\Rightarrow \,{{({{\sin }^{-1}})}^{2}}\,=\frac{{{\pi }^{2}}}{4}\]             \[\therefore \,\,\,\,{{({{\sec }^{-1}}\,y)}^{2}}\,+{{({{\tan }^{-1}}\,z)}^{2}}\,=0\]             or         \[\,{{\sec }^{-1}}\,y={{\tan }^{-1}}\,z=0\]             \[{{\sin }^{-1}}x=\pm \,\frac{\pi }{2}\,\Rightarrow \,x=\pm \,1,\,\,y=1,\,\,z=0\]             \[\therefore \,\,(1,\,\,1,\,\,0)\,\,\And \,\,(-1,\,\,1,\,\,0)\]


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