Q54 of 63 Page 202

The equation of the ellipse whose focus is (1, –1), the directrix the line x – y – 3 = 0 and eccentricity is

Focus (S) = (1, -1) Directrix is x – y – 3 = 0 &


As, for any point P (x,y) on the ellipse,


Distance from focus to the point (x,y) = e (Distance from (x,y) to the foot of perpendicular on directrix)


Perpendicular Distance (Between a point and line) = , whereas the point is and the line is expressed as ax + by + c = 0


Using Distance Formula,





Squaring both the sides,




8[x2 - 2x + 1 + y2 + 2y + 1] = x2 - 6x - 2xy + y2 + 6y + 9


8x2 - 16x + 16 + 8y2 + 16y = x2 - 6x - 2xy + y2 + 6y + 9


7x2 - 10x + 2xy + 7y2 + 10y + 7 = 0


Hence the required equation is 7x2 - 10x + 2xy + 7y2 + 10y + 7 = 0


OPTION (A) is the correct answer.

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