Answer: 18/5.
- A 9/5
- B 18/5
- C 5/3
- D 10/3
Correct answer: B. 18/5
Explanation: Latus rectum = 2b<sup>2</sup>/a = 2(9)/5 = 18/5.
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.