NCERT Class XI Mathematics - Conic Sections - Solutions

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Question : 54
Total: 71
Vertices (±2, 0), foci (±3, 0)
Solution:  
Vertices are (±2, 0) which lie on x-axis.
So the equation of hyperbola in standard form is
x2
a
y2
b2
= 1
∴ Vertices are (±2, 0) ⇒ a = 2; Foci are (±3, 0) ⇒ ae = 3
Now, ae = 3 ⇒ e =
3
a
⇒ e =
3
2

We know that b = ae21 ⇒ b = 2
9
4
1
= 2
5
2
= 5
Thus required equation of hyperbola is
x2
(2)2
y2
(5)2
= 1 ⇒ x24
y2
5
= 1
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