If the eccentricity e of the hyperbola x^2 a^2 - y^2 b^2 = 1, passing through (6, 4√3), satisfies 15(e^2 + 1) = 34e, then the length of the latus…
JEE Main 2026 — Mathematics Coordinate Geometry
2026mcqmedium
If the eccentricity e of the hyperbola a2x2−b2y2=1, passing through (6,43), satisfies 15(e2+1)=34e, then the length of the latus rectum of the hyperbola b2x2−2(a2+1)y2=1 is:
Official previous-year question
Held on 6 Apr 2026 · Verified 6 Jul 2026.
Options
A
10
B
20
C
25
D
30
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Solution
The given equation of the hyperbola is a2x2−b2y2=1.
Since it passes through (6,43), we have:
a236−b248=1
The eccentricity e satisfies 15(e2+1)=34e.
15e2−34e+15=0
(3e−5)(5e−3)=0
Since the eccentricity of a hyperbola is e>1, we get e=35.
We know that b2=a2(e2−1).
b2=a2(925−1)=916a2
Substituting b2 into the first equation:
a236−916a248=1
a236−a227=1
a29=1⇒a2=9
Then, b2=916×9=16.
The second hyperbola is given by b2x2−2(a2+1)y2=1.
Substituting the values of a2 and b2:
16x2−2(9+1)y2=1
16x2−20y2=1
Here, A2=16⇒A=4 and B2=20.
The length of the latus rectum is A2B2.
Length of latus rectum =42×20=10.
Answer: 10
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