Let S and S' be the foci of the ellipse and B be any one of the extremities of its minor axis. If 
S'BS is a right angled triangle with right angle at B and area (
S'BS) = 8 sq. units, then the length of a latus rectum of the ellipse is
(a)
2
(b)
2
(c)
4
(d)
4
Let S and S' be the foci of the ellipse and B be any one of the extremities of its minor axis. If S'BS is a right angled triangle with right angle at B and area ( S'BS) = 8 sq. units, then the length of a latus rectum of the ellipse is
(a)
2
(b)
2
(c)
4
(d)
4
Question ID - 57361 | SaraNextGen Top Answer
Let S and S' be the foci of the ellipse and B be any one of the extremities of its minor axis. If S'BS is a right angled triangle with right angle at B and area ( S'BS) = 8 sq. units, then the length of a latus rectum of the ellipse is
(a)
2
(b)
2
(c)
4
(d)
4
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Let S and S' be the foci of the ellipse and B be any one of the extremities of its minor axis. If |
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|
(a) |
2 |
(b) |
2 |
|
(c) |
4 |
(d) |
4 |
1 Answer
127 votes
Answer Key / Explanation : (c) -
mSB . mS’B = −1
b2 = a2e2 … (i)
S’B. SB =8
S’B. SB =16
a2e2 + b2 = 16 … (ii)
b2 = a2 (1−e)2 … (iii)
using (i), (ii), (iii) a=4
b= 2
e=
∴ l(L.R) = 
= 4
127 votes
Answer Link
127