If the distance between the foci of an ellipse is 6 and the distance between its directrices is 12, then the length of its latus rectum is:
If the distance between the foci of an ellipse is 6 and the distance between its directrices is 12, then the length of its latus rectum is:
Option 1 -
√3
Option 2 -
3√2
Option 3 -
3/√2
Option 4 -
2√3
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1 Answer
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Correct Option - 2
Detailed Solution:Given 2ae = 6 and 2a/e = 12.
From these, ae = 3 and a/e = 6.
Multiplying the two equations: (ae) (a/e) = 3 * 6 => a² = 18.
We know that b² = a² (1 - e²) = a² - a²e² = 18 - (ae)² = 18 - 3² = 18 - 9 = 9.
The length of the latus rectum (L.R.) is 2b²/a.
L.R. = 2 * 9 / √18 = 18 / (3√2) = 6/√2 = 3√2.
Similar Questions for you
ae = 2b
Or 4 (1 – e2) = e2
4 = 5e2 ->
If two circles intersect at two distinct points
->|r1 – r2| < C1C2 < r1 + r2
| r – 2| < < r + 2
|r – 2| < 5 and r + 2 > 5
–5 < r 2 < 5 r > 3 … (2)
–3 < r < 7 (1)
From (1) and (2)
3 < r < 7
x2 – y2 cosec2q = 5
x2 cosec2q + y2 = 5
and
->
1 + sin2q = 7 – 7 sin2q
->8sin2q = 6
->
->

Slope of axis =
⇒ 2y – 6 = x – 2
⇒ 2y – x – 4 = 0
2x + y – 6 = 0
4x + 2y – 12 = 0
α + 1.6 = 4 ⇒ α = 2.4
β + 2.8 = 6 ⇒ β = 3.2
Ellipse passes through (2.4, 3.2)
⇒
&
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