NCERT Class XI Mathematics - Conic Sections - Solutions

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Question : 57
Total: 71
Foci (±5, 0), the transverse axis is of length 8.
Solution:  
Here foci are (±5, 0) which lie on x-axis.
So the equation of the hyperbola in standard form is
x2
a2
y2
b2
= 1.
Now, Foci are (±5, 0) ⇒ ae = 5, Length of transverse axis, 2a = 8 ⇒ a = 4
Now, ae = 5 ⇒ e =
5
a
⇒ e =
5
4

We know that b = ae21 ⇒ b = 4
25
16
1
= 4 ×
3
4
= 3
Thus required equation of hyperbola is
x2
(4)2
y2
(3)2
= 1 ⇒
x2
16
y2
9
= 1.
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