Question
Sun January 01, 2012 By: Sunny Acharjee

what is the equation of ellipse whose centre is the origin, major axis of length 10 units and its foci (0, 3)

Expert Reply
Sun January 01, 2012
Let the length of major axis be 2a and foci be (0,c),
therefore 2a = 10 and c = 3
that is a = 5 and c = 3
Now if 2b is the length of minor axis, we have
b2 = a2 - c2 = 25 - 9 = 16
Since foci lie on y-axis, the equation of ellipse is
x2/b2 + y2/a2 = 1
On putting the values of a and b we get 
x2/16 + y2/25 = 1
 
 
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