CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2000

  • question_answer
    The foot of the perpendicular from the point (3, 4) on the line\[3x-4y+5=0\]is:

    A)  \[\left( \frac{81}{25},\frac{92}{25} \right)\]                        

    B)         \[\left( \frac{92}{25},\frac{81}{25} \right)\]                        

    C)         \[\left( \frac{46}{25},\frac{54}{25} \right)\]                        

    D)         \[\left( \frac{-81}{25},\frac{-92}{25} \right)\]

    E)         \[\left( \frac{81}{25},\frac{108}{25} \right)\]

    Correct Answer: A

    Solution :

    Let M be the foot of perpendicular from P(3, 4) on the line\[3x-4y+5=0\]. Then M is the point of intersection of\[3x-4y+5=0\]and line passing through P (3, 4) and perpendicular to \[3x-4y+5=0\]                       ...(i) Equation of line perpendicular to \[3x-4y+5=0\]is \[4x+3y+\lambda =0\] This passes through (3, 4) \[\Rightarrow \]               \[12+12+\lambda =0\] \[\Rightarrow \]               \[\lambda =-24\] \[\therefore \]Equation is \[4x+3y-24=0\]                 ...(ii) On solving Eqs. (i) and (ii), we get \[y=92/25,\text{ }x=81/25\] \[\therefore \]Required point is (81 / 25, 92/ 25).


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