Question
The eccentricity of an ellipse, with its centre at the origin, is 
. If one of the directrices is x = 4, then the equation of the ellipse is-
- 3x2 + 4y2 =1
- 3x2 + 4y2 =12
- 4x2 + 3y2 =12
- 4x2 + 3y2 =1
Hint:
find the values of a and b and substitute those values in the standard equation,
The correct answer is: 3x2 + 4y2 =12
3x2+4y2=12
given,
a/e=4
e=1/2
a=2
b=√3
x2/a2+y2/b2=1
x2/4+y2/3=1
3x2+4y2=12
standard equation of ellipse is
x2/a2+y2/b2=1
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