JEE Main & Advanced Mathematics Straight Line Question Bank Slope of line, Equation of line in different forms

  • question_answer
    A line passing through origin and is perpendicular to two given lines \[2x+y+6=0\] and \[4x+2y-9=0\], then the ratio in which the origin divides this line is [DCE 2005]

    A)            1 : 2                                          

    B)            2 : 1

    C)            4 : 3

    D)            3 : 4

    Correct Answer: C

    Solution :

               Equation of line Perpendicular to \[2x+y+6=0\] passes through (0, 0) is \[x-2y=0\]            Now point of intersection of \[x-2y=0\] and \[2x+y+6=0\]is \[\left( \frac{-12}{5},\frac{-6}{5} \right)\] and point of intersection of \[x-2y=0\] and \[4x+2y-9=0\] is \[\left( \frac{9}{5},\frac{9}{10} \right)\].            Now say origin divide the line \[x-2y=0\] in the ratio \[\lambda :1\]            \ \[x=\frac{\frac{9}{5}\lambda -\frac{12}{5}}{\lambda +1}=0\Rightarrow \frac{9}{5}\lambda =\frac{12}{5}\], \[\therefore \lambda =\frac{4}{3}\]                    Thus origin divides the line \[x=2y\], in the ratio 4 : 3.


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