NCERT Class XI Mathematics - Conic Sections - Solutions

© examsnet.com
Question : 38
Total: 71
Vertices (0, ±13), foci (0, ± 5)
Solution:  
Clearly, the foci (0, ±5) lie on y-axis.
∴ The equation of ellipse in standard form is
x2
a2
+
y2
b2
= 1
Now, vertices are (0, ±13) ⇒ a = 13, foci are (0, ±5) ⇒ c = 5
Also, we know that c2 = a2b2
(5)2 = (13)2b2b2 = 169 – 25 = 144.
Hence the required equation of ellipse is
x2
144
+
y2
169
= 1
© examsnet.com
Go to Question: