Select the most suitable statement.

2023

Select the most suitable statement.

Answer: D. More than one of the aboveConceptA statement of the form “Every A is B” means that the set A is contained in the set B. A statement of the form “No A is B” means that the two sets have…

  1. A.

    Every circle is an ellipse.

  2. B.

    No circle is a hyperbola.

  3. C.

    Every square is a rectangle.

  4. D.

    More than one of the above

  5. E.

    None of the above

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Correct answer: D

Concept

A statement of the form “Every A is B” means that the set A is contained in the set B. A statement of the form “No A is B” means that the two sets have no common member.

In inclusive geometric definitions, a more specialised figure can belong to a broader family when it satisfies all defining properties of that family.

Application

  1. A circle is an ellipse whose two semi-axes are equal; equivalently, its eccentricity is 0. Therefore “Every circle is an ellipse” holds under the standard inclusive definition.

  2. A circle is an ellipse with eccentricity 0, whereas a hyperbola has eccentricity greater than 1. Thus no non-degenerate circle is a hyperbola.

  3. A square has four right angles and opposite sides parallel, so it satisfies every defining condition of a rectangle. Therefore every square is a rectangle.

Contrast and cross-check

  • “Every circle is an ellipse” is supported by the equal-semi-axis special case.

  • “No circle is a hyperbola” follows from the mutually different conic classes and eccentricities.

  • “Every square is a rectangle” follows from the inclusive hierarchy of quadrilaterals.

  • “None of the above” would require all three substantive statements to fail, which the definition checks rule out.

Result

Three substantive statements hold, so the suitable set-referential choice is “More than one of the above”.

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