Skip to main content
Back to Conic Sections
JEE Main 2023
Conic Sections
Ellipse
Hard

Question

Let E1:x29+y24=1\mathrm{E}_1: \frac{x^2}{9}+\frac{y^2}{4}=1 be an ellipse. Ellipses Ei\mathrm{E}_{\mathrm{i}} 's are constructed such that their centres and eccentricities are same as that of E1\mathrm{E}_1, and the length of minor axis of Ei\mathrm{E}_{\mathrm{i}} is the length of major axis of Ei+1(i1)E_{i+1}(i \geq 1). If AiA_i is the area of the ellipse EiE_i, then 5π(i=1Ai)\frac{5}{\pi}\left(\sum\limits_{i=1}^{\infty} A_i\right), is equal to _______.

Answer: 1

Solution

This problem involves a sequence of ellipses, each defined by specific geometric properties related to the previous one. We will utilize the standard formulas for ellipses, including eccentricity and area, and then identify a geometric progression to find the sum of their areas.


1. Key Concepts and Formulas for Ellipses

For 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 aa is the semi-major axis and bb is the semi-minor axis, with a>ba > b.
  • Length of Major Axis: 2a2a
  • **Length

Practice More Conic Sections Questions

View All Questions