JEE Main & Advanced Mathematics Straight Line Question Bank Distance between two lines, Perpendicular distance of the line from a point Position of point w.r.t. line

  • question_answer
    Distance between the lines \[5x+3y-7=0\] and \[15x+9y+14=0\] is                                     [Kerala (Engg.) 2002]

    A)            \[\frac{35}{\sqrt{34}}\]            

    B)            \[\frac{1}{3\sqrt{34}}\]

    C)            \[\frac{35}{3\sqrt{34}}\]          

    D)            \[\frac{35}{2\sqrt{34}}\]

    Correct Answer: C

    Solution :

               Given lines are \[5x+3y-7=0\]                                  .....(i)                    and  \[15x+9y+14=0\] or \[5x+3y+\frac{14}{3}=0\]   .....(ii)                    lines (i) and (ii) are parallel. Since \[{{c}_{1}}\] and \[{{c}_{2}}\] are of opposite signs, therefore the lines are on opposite sides of the origin. So the distance between them is                    \[=\left| \frac{{{c}_{1}}}{\sqrt{a_{1}^{2}+b_{1}^{2}}} \right|+\left| \frac{{{c}_{2}}}{\sqrt{a_{2}^{2}+{{b}_{2}}}} \right|\]\[=\left| \frac{-7}{\sqrt{34}} \right|+\left| \frac{14}{3\sqrt{34}} \right|\]\[=\frac{35}{3\sqrt{34}}.\]


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