Let an ellipse x2a2+ y2b2=1, a<b, pass through the point (4, 3) and have eccentricity 53. Then the length of its latus rectum is :
- 4 53
- 2 5
- 7 53
- 8 53
Answer
(4) 8 53
Solution
∵ a<b, the major axis lies along the y-axis.
e2=1- a2b2= 59 a2= 4b29
(4,3) lies on the ellipse: 16a2+ 9b2=1
36b2+ 9b2=1 b2=45, a2=20
Length of latus rectum = 2a2b= 403 5= 8 53
Answer: (4)