Answer: (±4, 0).
- A (±3, 0)
- B (±4, 0)
- C (±5, 0)
- D (0, ±4)
Correct answer: B. (±4, 0)
Explanation: From a2=25, b2=9, c2=a2-b2=16, c=4. Foci are at (±c, 0) = (±4, 0).
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.