JEE Main 2019 Mathematics question
Let S and S′ be the foci of an ellipse and B be any one of the extremities of its minor axis. If ΔS′BS is a right angled triangle with right angle at B and area (ΔS′BS) = 8 sq. units, then the length of a latus rectum of the ellipse is:
Answer: (C)
Solution
b = ae and area = b · ae = 8 ⇒ = 8, = 16 ⇒ LR = 2b/a = 4.