Which solid is perfectly round and has no faces, edges, or vertices?

Which solid is perfectly round and has no faces, edges, or vertices?

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

Answer: (A)

A shape that is perfectly round all over means every point on its surface is the same distance from the center, so there are no flat faces, no edges, and no corners. That describes a sphere, like a ball. The other shapes have flat parts or corners: a cube has flat faces, edges where faces meet, and vertices where edges meet; a cylinder has flat ends and a curved side where surfaces meet; a pyramid has a pointed top with edges and vertices. So the only shape without faces, edges, or vertices is the sphere.

A shape that is perfectly round all over means every point on its surface is the same distance from the center, so there are no flat faces, no edges, and no corners. That describes a sphere, like a ball. The other shapes have flat parts or corners: a cube has flat faces, edges where faces meet, and vertices where edges meet; a cylinder has flat ends and a curved side where surfaces meet; a pyramid has a pointed top with edges and vertices. So the only shape without faces, edges, or vertices is the sphere.