$\mathrm{p}$ is the length of perpendicular from the origin to the line whose intercepts on the axes are a…

$\mathrm{p}$ is the length of perpendicular from the origin to the line whose intercepts on the axes are a and $\mathrm{b}$ respectively, then $\frac{1}{\mathrm{a}^2}+\frac{1}{\mathrm{~b}^2}$ equals
  1. $\mathrm{p}^2$
  2. $\frac{2}{\mathrm{p}^2}$
  3. $\frac{1}{\mathrm{p}^2}$
  4. $\frac{1}{2 p^2}$

Solution

Let the equation of the line be $\frac{x}{\mathrm{a}}+\frac{y}{\mathrm{~b}}=1$ According to the given condition, $\begin{aligned} & \mathrm{p}=\left|\frac{\mathrm{ab}}{\sqrt{\mathrm{a}^2+b^2}}\right| \\ & \Rightarrow \frac{\mathrm{a}^2+\mathrm{b}^2}{\mathrm{a}^2 \mathrm{~b}^2}=\frac{1}{\mathrm{p}^2} \\ & \Rightarrow \frac{1}{\mathrm{a}^2}+\frac{1}{\mathrm{~b}^2}=\frac{1}{\mathrm{p}^2} \end{aligned}$

Asked in: MHT CET 2023 (14 May Shift 1)

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