RAJASTHAN ­ PET Rajasthan PET Solved Paper-2006

  • question_answer
    The circle \[{{x}^{2}}+{{y}^{2}}-6x-10y+p=0\]neither touches the axes nor intersect. If point (1, 4) lies inside the circle, then

    A)  \[0<p<29\]        

    B)  \[25<p<35\]

    C)  \[25<p<29\]       

    D)  None of these

    Correct Answer: C

    Solution :

     Given, circle is\[{{x}^{2}}+{{y}^{2}}-6x-10y+p=0\]   ...(i) its centre is (3, 5) and radius, \[r=\sqrt{9+25-p}\] \[=\sqrt{34-p}\] Since the circle neither touches the axes nor intersect \[\therefore \] \[x-\]coordinate of centre\[>r\] y-coordinate of centre\[>r\] and           \[S(1,4)<0\] \[\Rightarrow \] \[-3>\sqrt{34-p}\]and \[5>\sqrt{34-p}\] On squaring, we get \[9>34-p\] and\[25>34-p\] \[\Rightarrow \]    \[p>34-9\]and \[p>34-25\] \[\Rightarrow \]    \[p>25\]and \[p>9\]                ...(ii) Now, put\[x=1,\text{ }y=4\]in Eq. (i), we get \[1+16-6-40+p<0\] \[\Rightarrow \]               \[p<29\]         ...(ii) Hence, from Eqs. (ii) and (iii), we get \[25<p<29\]and \[9<p<29\]


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