Suppose $A B$ is a focal chord of the parabola $y^2=12 x$ of length $l$ and slope $\mathrm{m} < \sqrt{3}$.…

Suppose $A B$ is a focal chord of the parabola $y^2=12 x$ of length $l$ and slope $\mathrm{m} < \sqrt{3}$. If the distance of the chord $\mathrm{AB}$ from the origin is $\mathrm{d}$, then $l \mathrm{~d}^2$ is equal to _______

Solution


$\begin{aligned} & \ell=4 \mathrm{a} \operatorname{cosec}^2 \theta \\ & \ell=12 \times \frac{9}{\mathrm{~d}^2} \\ & \ell \mathrm{d}^2=108\end{aligned}$

Asked in: JEE Main 2024 (05 Apr Shift 1)

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