NCERT Class XI Mathematics - Conic Sections - Solutions

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Question : 53
Total: 71
49y216x2 = 784
Solution:  
Given equation of hyperbola is 49y216x2 = 784
i.e.,
49y2
784
16x2
784
= 1 ⇒
y2
16
x2
49
= 1
which is of the form
y2
a2
x2
b2
= 1.
The foci and vertices of the hyperbola lie on y-axis.
Now, a2 = 16 ⇒ a = 4 and b2 = 49 ⇒ b = 7
Also, c2 = a2+b2 = 16 + 49 = 65 ⇒ c = 65
∴ Coordinates of foci are (0, ±c) i.e. (0,±64)
Coordinates of vertices are (0, ±a) i.e. (0, ±4)
Eccentricity (e) =
c
a
=
65
4

Length of latus rectum =
2b2
a
=
2×49
4
=
49
2
.
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