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

  • question_answer
    The number of lines that are parallel to \[2x+6y+7=0\] and have an intercept of length 10 between the coordinate axes is

    A)            1    

    B)            2

    C)            4    

    D)            Infinitely many

    Correct Answer: B

    Solution :

               The equation of any line parallel to \[2x+6y+7=0\]is\[2x+6y+k=0\].                    This meets the axes at \[A\left( -\frac{k}{2},0 \right)\]and\[B\left( 0,-\frac{k}{6} \right)\].                     By hypothesis, \[AB=10\]                    \[\Rightarrow \sqrt{\frac{{{k}^{2}}}{4}+\frac{{{k}^{2}}}{36}}=10\Rightarrow \sqrt{\frac{10{{k}^{2}}}{36}}=10\]                    Þ \[10{{k}^{2}}=3600\Rightarrow k=\pm 6\sqrt{10}\].                    Hence there are two lines given by\[2x+6y\pm 6\sqrt{10}=0\].


You need to login to perform this action.
You will be redirected in 3 sec spinner