Which of the following best describes a tetrahedron?

Which of the following best describes a tetrahedron?

• A. A pyramid with four plane faces
• B. A cube with six faces
• C. A cylinder
• D. A cone

Answer: (A)

A tetrahedron is a solid with four triangular faces, four vertices, and six edges. Describing it as a pyramid with four plane faces fits exactly because a triangular base plus three triangular sides forms a pyramid with four faces in total. The other shapes don’t match: a cube has six square faces; a cylinder has a curved surface with two flat ends; a cone has a circular base and a single curved surface that narrows to a point.

A tetrahedron is a solid with four triangular faces, four vertices, and six edges. Describing it as a pyramid with four plane faces fits exactly because a triangular base plus three triangular sides forms a pyramid with four faces in total. The other shapes don’t match: a cube has six square faces; a cylinder has a curved surface with two flat ends; a cone has a circular base and a single curved surface that narrows to a point.