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JEE Mains · Maths · STD 11 - 10.2 parabola,ellipse,hyperbola

Let the length of the focal chord \(P Q\) of the parabola \(y^2=12 x\) be \(15\) units. If the distance of \(P Q\) from the origin is \(\mathrm{p}\), then \(10 \mathrm{p}^2\) is equal to ...........

  1. A \(54\)
  2. B \(21\)
  3. C \(97\)
  4. D \(72\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(72\)

Step-by-step Solution

Detailed explanation

\( \text { length of focal chord }=4 a \operatorname{cosec}^2 \theta=15 \) \( 12 \operatorname{cosec}^2 \theta=15 \) \( \sin ^2 \theta=\frac{4}{5} \) \( \tan ^2 \theta=4 \) \( \tan \theta=2 \) \( \text { equation } \frac{y-0}{x-3}=2 \) \( y=2 x-6 \) \( 2 x-y-6=0 \)…