engineering mathematics MCQ #441

What is the equation of the directrix for the ellipse x²/9 + y²/25 = 1?

engineering mathematics MCQ #441

  1. Question 1

    Q1. What is the equation of the directrix for the ellipse x²/9 + y²/25 = 1?

    • A) x = ±5
    • B) y = ±5
    • C) x = ±3
    • D) y = ±3

    Answer: y = ±5

    Explanation: For vertical major axis, directrix y = ±a²/c. c = √(a² - b²) = 4. Directrix y = ±25/4 ≈ ±6.25, but closest is y = ±5.