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 parallel lines \[3x+4y+7=0\] and \[3x+4y-5=0\] is                                            [RPET 2003]

    A)            \[\frac{2}{5}\]                           

    B)            \[\frac{12}{5}\]

    C)            \[\frac{5}{12}\]                         

    D)            \[\frac{3}{5}\]

    Correct Answer: B

    Solution :

               \[{{d}_{1}}=\] distance of perpendicular from \[(0,\,0)\] to \[3x+4y+7=0\]                    \[{{d}_{1}}=\frac{3\times 0+4\times 0+7}{\sqrt{{{3}^{2}}+{{4}^{2}}}}=\frac{7}{5}\]                    \[{{d}_{2}}=\frac{3\times 0+4\times 0+(-5)}{\sqrt{{{3}^{2}}+{{4}^{2}}}}=\frac{-5}{5}\]                    \ Required distance \[=\left| \,{{d}_{1}}-{{d}_{2}} \right|\]\[=\left| \,\frac{7}{5}-\left( \frac{-5}{5} \right)\, \right|=\frac{12}{5}.\]


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