JEE Main & Advanced JEE Main Paper (Held On 25 April 2013)

  • question_answer
                    If the image of point P(2,3) in a line L is Q(4,5), the image of point R(0,0) in the same line is :     JEE Main Online Paper ( Held On 25  April 2013 )

    A)                 (2, 2)                                     

    B)                                        (4, 5)

    C)                                        (3, 4)                     

    D)                                        (7, 7)

    Correct Answer: D

    Solution :

                    Mid-point of P(2,3) and Q(4,5) =(3,4) Slope of PQ=1 Slope of the line L=-l Mid-point (3,4) lies on the line L. Equation of line L, \[y-4=-1(x-3)\Rightarrow x+y-7=0\]                        ?(i) Let image of point R(0,0) be \[S({{x}_{1}},{{y}_{1}})\] Mid-point of\[RS=\left( \frac{{{x}_{1}}}{2},\frac{{{y}_{1}}}{2} \right)\] Mid-point \[\left( \frac{{{x}_{1}}}{2},\frac{{{y}_{1}}}{2} \right)\]lies on the line (i) \[\therefore \]\[{{x}_{1}}+{{y}_{1}}=14\] Slope of \[RS=\frac{{{y}_{1}}}{{{x}_{1}}}\] Since \[RS\bot \]line L \[\therefore \]\[\frac{{{y}_{1}}}{{{x}_{1}}}\times (-1)=-1\] \[\therefore \]\[{{x}_{1}}={{y}_{1}}\]From (ii) and (iii),\[{{x}_{1}}={{y}_{1}}=7\] Hence the image of R= (7,7)


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