JEE MainMathematicsEllipse
Let an ellipse with its major axis along the x-axis have foci S and S' . If the ellipse passes through the point P(2, 3) and the perimeter of the triangle PSS' is 12 , then the eccentricity of the ellipse is
Options
- A1 2
- B3 4
- C1 4
- D7 2
Correct answer
A. 1 2
Step-by-step solution
Let the equation of the ellipse be x^2 a^2 + y^2 b^2 = 1 , where a > b . For any point P on the ellipse, the sum of its focal distances is SP + S'P = 2a . The distance between the foci is SS' = 2ae . The perimeter of the triangle PSS' is given as 12 : SP + S'P + SS' = 12 2a + 2ae = 12 a + ae = 6 ae = 6 - a We know the relation b^2 = a^2 - (ae)^2 . Substituting ae = 6 - a : b^2 = a^2 - (6 - a)^2 = a^2 - (36 - 12a + a^2) = 12a - 36 Since the ellipse passes through P(2, 3) , we substitute x = 2 and y = 3 into the equa