JCECE Engineering JCECE Engineering Solved Paper-2010

  • question_answer
    The equation of tangent parallel to \[y=x\] drawn to\[\frac{{{x}^{2}}}{3}-\frac{{{y}^{2}}}{2}=1\], is

    A) \[x-y+1=0\]                       

    B) \[x-y+2=0\]

    C) \[x+y-1=0\]                       

    D) \[x+y-2=0\]

    Correct Answer: A

    Solution :

    Let equation of tangent parallel to \[y=x\] drawn to\[\frac{{{x}^{2}}}{3}-\frac{{{y}^{2}}}{2}=1\]is\[y=x+c\]        \[(\because \,\,m=1)\] We know that, for tangency                 \[{{c}^{2}}={{a}^{2}}{{m}^{2}}-{{b}^{2}}\] \[\Rightarrow \]               \[{{c}^{2}}=3\cdot 1-2\]                 \[(a=3,\,\,b=2\]from given hyperbola) \[\Rightarrow \]               \[{{c}^{2}}=1\] \[\Rightarrow \]               \[c=\pm 1\] Hence, equation of tangent is                 \[y=x\pm 1\] \[\Rightarrow \]               \[x-y=\pm 1\] \[\Rightarrow \]               \[x-y\mp 1=0\]


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