. The foci of the ellipse
25 (x + 1)2 + 9 (y + 2)2 = 225 are at
A. (-1, 2) and (-1, -6)
B. (-2, 1) and (-2, 6)
C. (-1, -2) and (-2, -1)
D. (-1, -2) and (-1, -6).
Best Answer
Ans: A
Sol: The given equation is 25 ( x+ 1)2 + 9 ( y + 2) 2 = 225
.PNG)
Centre of the ellipse º ( -1, -2 )
and a = 3 , b = 5, so that a< b Þ 3 = .PNG)
or e2 = 1- 9/ 25 = 16/25 Þ e = 4/ 5
Hence foci are ( -1, -2 - 5´ 4/5) and ( -1 , -2 + 5 ´ 4/5)
i.e. foci are (-1 , -6 ) and (-1, 2) .
Hence (A) is the correct answer.
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