Which solid has no edges?

Which solid has no edges?

• A. Sphere
• B. Cylinder
• C. Cube
• D. Pyramid

Answer: (A)

Edges are the lines where two faces meet. A sphere has a single, smooth curved surface with no flat faces, so there are no lines where faces come together—no edges. A cylinder has a curved side plus two circular bases, and the places where the curved surface meets each base form edges. A cube has many straight edges where its square faces meet. A pyramid also has edges where its triangular faces join. So the sphere is the one with no edges.

Edges are the lines where two faces meet. A sphere has a single, smooth curved surface with no flat faces, so there are no lines where faces come together—no edges. A cylinder has a curved side plus two circular bases, and the places where the curved surface meets each base form edges. A cube has many straight edges where its square faces meet. A pyramid also has edges where its triangular faces join. So the sphere is the one with no edges.