JEE Mains · Maths · STD 11 - 10.2 parabola,ellipse,hyperbola
Suppose \(A B\) is a focal chord of the parabola \(\mathrm{y}^2=12 \mathrm{x}\) 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 ....................
- A \(128\)
- B \(108\)
- C \(164\)
- D \(173\)
Answer & Solution
Correct Answer
(B) \(108\)
Step-by-step Solution
Detailed explanation
\( \ell=4 \mathrm{a} \operatorname{cosec}^2 \theta \) \( \ell=12 \times \frac{9}{\mathrm{~d}^2} \) \( \ell \mathrm{d}^2=108\)
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