EllipseHard
Question
Let tangents drawn from point (0,5) to the ellipse
= 1 are perpendicular and meet major axis of ellipse at points A & B. A hyperbola ′H′ is drawn whose eccentricity is reciprocal of eccentricity of ellipse & whose foci are points A & B, then-
Options
A.eccentricity of ellipse is 
B.hyperbola ′H′ is
= 25
C.C) hyperbola ′H′ is 4x2 - 12y2 = 75
D.Length of latus rectum of ellipse is 
Solution
(0,5) lies on director circle of ellipse i.e.
x2 + y2 = a2 + 5
⇒ a2 = 20
⇒ eccentricity of ellipse is e =
Let tangents are y = mx + 5
∵ c2 = a2m2 + b2 ⇒ 25 = 20m2 + 5 ⇒ m = ± 1
points A & B are (5, 0) & (-5, 0)
for hyperbola ′H′ foci are (±5,0) & e =
′H′ is 4x2 - 12y2 = 75
x2 + y2 = a2 + 5
⇒ a2 = 20
⇒ eccentricity of ellipse is e =
Let tangents are y = mx + 5
∵ c2 = a2m2 + b2 ⇒ 25 = 20m2 + 5 ⇒ m = ± 1
points A & B are (5, 0) & (-5, 0)
for hyperbola ′H′ foci are (±5,0) & e =
′H′ is 4x2 - 12y2 = 75
Create a free account to view solution
View Solution FreeMore Ellipse Questions
Arrangement of the following ellipses in ascending order of the radii of their director circles (P) 4x2 + 9y2 = 36 (Q) 3...The line passing through the extremity A of the major axis and extremity B of the minor axis of the ellipse x2 + 9y2 = 9...From the point (λ, 3) tangents are drawn to = 1 and are perpendicular to each other then λ =...PQ is a double ordinate of the ellipse x2 + 9y2 = 9, the normal at P meets the diameter through Q at R, then the locus o...A focus of an ellipse is at the origin. The directrix is the line x = 4 and the eccentricity is 1/2. Then the length of ...