The nearest point on the line $3 x+4 y=12$ from the origin is

The nearest point on the line $3 x+4 y=12$ from the origin is
  1. $\left(\frac{36}{25}, \frac{48}{25}\right)$
  2. $\left(3, \frac{3}{4}\right)$
  3. $\left(2, \frac{3}{2}\right)$
  4. None of these

Solution

If ' $\mathrm{D}$ ' be the foot of altitude, drawn from origin to the given line, then ${ }^{4} \mathrm{D}^{\prime}$ is the required point. Let $\angle \mathrm{OBA}=\theta$ $\Rightarrow \tan \theta=4 / 3$ $\Rightarrow \angle \mathrm{DOA}=\theta$ $\begin{aligned} &\text { we have } \quad \mathrm{OD}=12 / 5 \text { . }\\ &\text { If } D \text { is }(h, k) \text { then } h=O D \cos \theta, k=O D \sin \theta\\ &\Rightarrow \mathrm{h}=36 / 25, \mathrm{k}=48 / 25 . \end{aligned}$

Asked in: BITSAT 2012

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