Let e₁ and e₂ be the eccentricities of the ellipse, x²/25 + y²/b² = 1 (b < 5) and the hyperbola, x²/16 - y²/b² = 1 respectively satisfying e₁e₂ = 1. If α and β are the distances between the foci of the ellipse and the foci of the hyperbola respectively, then the ordered pair (α, β) is equal to :
Let e₁ and e₂ be the eccentricities of the ellipse, x²/25 + y²/b² = 1 (b < 5) and the hyperbola, x²/16 - y²/b² = 1 respectively satisfying e₁e₂ = 1. If α and β are the distances between the foci of the ellipse and the foci of the hyperbola respectively, then the ordered pair (α, β) is equal to :
Option 1 -
(8,10)
Option 2 -
(24/5, 10)
Option 3 -
(24/5, 12)
Option 4 -
(8,12)
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1 Answer
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Correct Option - 1
Detailed Solution:e? = √1-b²/25; e? = √1+b²/16
e? = 1
=> (e? )² = 1
=> (1 - b²/25) (1 + b²/16) = 1
=> 1 + b²/16 - b²/25 - b? / (25x16) = 1
=> (9b²)/ (16.25) - b? / (25.16) = 0
=> b²=9
e? = √1-9/25 = 4/5
e? = √1+9/16 = 5/4
α = 2 (5) (e? ) = 8
β = 2 (4) (e? ) = 10
(α, β) = (8,10)
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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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