Question

select the image that is not a polyhedron.

Explanation:

Step1: Recall the definition of a polyhedron

A polyhedron is a three - dimensional solid made up of flat polygonal faces, straight edges, and sharp vertices.

Step2: Analyze each image

• The first image (a triangular pyramid): It has triangular faces, straight edges, and vertices. So it is a polyhedron.
• The second image (a prism - like shape): It has polygonal (rectangular and parallelogram - like) faces, straight edges, and vertices. So it is a polyhedron.
• The third image (a cylinder): It has two circular faces (circles are not polygons) and a curved surface. So it is not a polyhedron.
• The fourth image (a polyhedron with multiple polygonal faces): It has polygonal faces, straight edges, and vertices. So it is a polyhedron.

Answer:

The cylinder (the third image) is not a polyhedron.