JCECE Engineering JCECE Engineering Solved Paper-2007

  • question_answer
    \[y\] intercept of line passes through \[(2,\,\,2)\] and is perpendicular to the line\[3x+y=3\], is

    A) \[\frac{1}{3}\]                                   

    B) \[\frac{2}{3}\]

    C) \[1\]                                     

    D) \[\frac{4}{3}\]

    Correct Answer: D

    Solution :

    Key Idea: Any line perpendicular to\[ax+by=c\]is\[bx-ay=k\]. Given line\[3x+y=3\] \[\therefore \]Line perpendicular to                 \[3x+y=3\]is\[x-3y=\lambda \] Also, it passes through\[(2,\,\,2)\] \[\Rightarrow \]               \[2-6=\lambda \Rightarrow \lambda =-4\] \[\therefore \]Equation of line\[x-3y=-4\]           ... (i) \[\therefore \]\[y\]intercept\[=\frac{-4}{-3}=\frac{4}{3}\] Alternate Method: Any line through\[(2,\,\,2)\] is             \[(y-2)=m(x-2)\]                               ...(i)                                                      \[(\because \]lines are\[\bot )\] \[\therefore \]  \[m=-\frac{1}{slope\,\,of\,\,line\,\,3x+y=3}\] \[\Rightarrow \]               \[m=\frac{1}{-3}=\frac{1}{3}\]                                    ? (ii) \[\therefore \]From (i) and (ii) Required line\[3(y-2)=(x-2)\] On putting \[x=0\], we get \[y=\frac{4}{3}\]is the \[y\] intercept.


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