Answer: 4a.
- A 4a
- B 2a
- C a
- D a/2
Correct answer: A. 4a
Explanation: The latus rectum of y² = 4ax has length 4a.
All four conics form a single family distinguished only by eccentricity: a circle is the most "closed" (e=0), an ellipse is an elongated closed curve, a parabola is the borderline open curve (e=1), and a hyperbola has two separate open branches (e>1).
Concept context
Study circles, parabolas, ellipses, and hyperbolas as curves formed by intersecting a plane with a double cone, with their standard equations and key properties.