EllipseHard
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
. If one of the directrices is x = 4, then the equation of the ellipse isOptions
A.3x2 + 4y2 = 1
B.3x2 + 4y2 = 12
C.4x2 + 3y2 = 12
D.4x2 + 3y2 = 1
Solution
Equation of directrix is x = a/e = 4 ⇒ a = 2
b2 = a2 (1 - e2) ⇒ b2 = 3
Hence equation of ellipse is 3x2 + 4y2 = 12.
b2 = a2 (1 - e2) ⇒ b2 = 3
Hence equation of ellipse is 3x2 + 4y2 = 12.
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