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JEE Main 2023
Conic Sections
Ellipse
Medium

Question

The line x=8x=8 is the directrix of the ellipse E:x2a2+y2b2=1\mathrm{E}:\frac{x^{2}}{a^{2}}+\frac{y^{2}}{b^{2}}=1 with the corresponding focus (2,0)(2,0). If the tangent to E\mathrm{E} at the point P\mathrm{P} in the first quadrant passes through the point (0,43)(0,4\sqrt3) and intersects the xx-axis at Q\mathrm{Q}, then (3PQ)2(3\mathrm{PQ})^{2} is equal to ____________.

Answer: 8

Solution

This problem requires a comprehensive understanding of ellipses, encompassing their definition, standard equation, properties related to foci and directrices, and the equation of a tangent. We will systematically determine the ellipse's parameters, locate the point of tangency, find the x-intercept of the tangent, and finally calculate the required distance.


1. Key Concepts and Formulas

Before diving into the calculations, let's recall the fundamental properties of an ellipse centered at the origin with its major axis along the x-axis:

  • Standard Equation: x2a2+y2b2=1\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1, where a>b>0a > b > 0.
  • Foci: $(\pm ae,

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