Q163 / 270 · NDA 2020 · Mathematics

If the foot of the perpendicular drawn from the point $(0, k)$ to the line $3 x-4 y-5=0$ is $(3,1)$, then what is the value of $k$ ?

  • A
    3
  • B
    4
  • Correct answer
    C
    5
  • D
    6

Solution

Slope of the line, $3 x-4 y-5=0$ is $m=\frac{3}{4}$ Slope of any line perpendicular to $3 x-4 y-5=0$ is $m^{\prime}=-\frac{4}{3}$. Figure
Now, required line passes through the points $(0, K)$ and $(3,1)$. $\therefore \frac{K-1}{0-3}=-\frac{4}{3} \Rightarrow K=5 \text {. }$

Hence, the correct answer is option: 'C'.

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