A cube is a special rectangular solid where all faces are squares. Which description is true?

A cube is a special rectangular solid where all faces are squares. Which description is true?

• A. A prism
• B. A cylinder
• C. A pyramid
• D. All edges are equal and faces are squares

Answer: (D)

Understanding what makes a cube unique: in a cube every edge is the same length and every face is a square. Those two facts together give six square faces and twelve equal edges, with right angles between edges. That combination exactly defines a cube, so describing it as having all edges equal and faces square is true and precise. The cube is also a kind of prism in a broad sense, since it has parallel bases and rectangular side faces, but that broader label doesn’t capture its defining feature set. The other shapes—cylinders and pyramids—don’t have flat square faces or equal-length edges throughout, so they don’t describe a cube.

Understanding what makes a cube unique: in a cube every edge is the same length and every face is a square. Those two facts together give six square faces and twelve equal edges, with right angles between edges. That combination exactly defines a cube, so describing it as having all edges equal and faces square is true and precise. The cube is also a kind of prism in a broad sense, since it has parallel bases and rectangular side faces, but that broader label doesn’t capture its defining feature set. The other shapes—cylinders and pyramids—don’t have flat square faces or equal-length edges throughout, so they don’t describe a cube.