JCECE Engineering JCECE Engineering Solved Paper-2007

  • question_answer
    The value of \[x\] satisfying\[{{\sin }^{-1}}x+{{\sin }^{-1}}(1-x)={{\cos }^{-1}}x\] are

    A) \[0\]                                     

    B) \[1,\,\,-1\]

    C) \[0,\,\,\frac{1}{2}\]                                        

    D)  none of these

    Correct Answer: C

    Solution :

    Given \[{{\sin }^{-1}}x+{{\sin }^{-1}}(1-x)={{\cos }^{-1}}x\] \[\Rightarrow \]\[{{\sin }^{-1}}x+{{\sin }^{-1}}(1-x)={{\sin }^{-1}}\sqrt{1-{{x}^{2}}}\] \[\Rightarrow \]               \[\sin [{{\sin }^{-1}}x+{{\sin }^{-1}}(1-x)]\] \[\Rightarrow \]               \[\sin [{{\sin }^{-1}}[x\sqrt{1-{{(1-x)}^{2}}}\] \[\Rightarrow \]               \[+(1-x)\sqrt{1-{{x}^{2}}}]=\sin {{\sin }^{-1}}(\sqrt{1-{{x}^{2}}})\] \[\Rightarrow \]      \[x\sqrt{1-{{(1-x)}^{2}}}+(1-x)\sqrt{1-{{x}^{2}}}=\sqrt{1-{{x}^{2}}}\] \[\Rightarrow \]               \[x\sqrt{2x-{{x}^{2}}}=\sqrt{1-{{x}^{2}}}x\] \[\Rightarrow \]               \[x(\sqrt{2x-{{x}^{2}}}-\sqrt{1-{{x}^{2}}})=0\] \[\Rightarrow \]               \[x=0\]or\[2x-{{x}^{2}}=1-{{x}^{2}}\] \[\Rightarrow \]               \[x=0\]or\[x=\frac{1}{2}\]


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