NTA Abhyas JEE Main2020MathematicsEllipsePractice
If the circle whose diameter is the major axis of the ellipse x 2 a 2 + y 2 b 2 = 1 a > b > 0 meets the minor axis at point P and the orthocentre of ∆ P F 1 F 2 lies on the ellipse, where F 1 and F 2 are the foci of the ellipse, then the square of the eccentricity of the ellipse is
Options
- A5 - 1 2
- B3 - 1
- C1 2
- D3 2
Correct answer
A. 5 - 1 2
Step-by-step solution
m F 1 B ⋅ m P F 2 = − 1 ⇒ a - 0 0 - a e × b - 0 0 - - a e = - 1 ⇒ b 2 a 2 = e 2 ⇒ e 4 + e 2 − 1 = 0 ∴ e 2 = 5 - 1 2