S and T are the foci of an ellipse and B is end point of the minor axis. If STB is an equilateral triangle, the eccentricity of the ellipse
is
(A)
1
4 (B)
1
3 (C)
1
2 (D)
2
3
aniket anand
12 Years agoGrade
2 Answers
Arun
6 Years ago
STB is equilateral Triangle. tan 60° = (OB/OS) = [b/{(1/2)2ae}] --- as d(foci) = 2ae ∴ √3 = (b/ae) ⇒ √(3)e = (b/a) Now e2 = 1 – (b2/a2) = 1 – 3e2 ∴ 4e2 = 1 i.e. e = ± (1/2) ⇒ e = (1/2) as 0
Vikas TU
6 Years ago
Dear student Question is not clear Please attach an image, We will happy to help you Good Luck Cheers
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