ExamBro
ExamBro
AP EAMCET · Maths · Ellipse

If the angle between the straight lines joining the foci and the ends of the minor axis of the ellipse \(\frac{x^2}{a^2}+\frac{y^2}{b^2}=1\) is \(90^{\circ}\), then it eccentricity is

  1. A \(1 / 2\)
  2. B \(1 / 4\)
  3. C \(1 / 3\)
  4. D \(1 / \sqrt{2}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(1 / \sqrt{2}\)

Step-by-step Solution

Detailed explanation

Apply pythagoras theorem, in \(\Delta A S_1 S_2\) \(\left(S_1 A\right)^2+\left(A S_2\right)^2=\left(S_1 S_2\right)^2\) \(a^2+a^2=(2 a e)^2\) \(\Rightarrow \quad 2 a^2=4 a^2 e^2\) \(\therefore \quad e=\frac{1}{\sqrt{2}}\)