geometry · Year 3 · AC9M3SP01
Faces, edges and vertices
Every 3D solid is built from three kinds of part. A face is a flat surface you could paint. An edge is the straight line where two faces meet. A vertex is a corner point where edges meet (the plural is vertices). A cube, for example, has 6 faces, 12 edges and 8 vertices. Count one kind at a time — trace every line for edges, poke every corner for vertices — and remember the parts you cannot see behind the solid still count.
Sample questions
How many vertices does a cube have?
- A cube has 6 faces, 12 edges and 8 vertices.
- Count the vertices: a cube has 8 vertices.
Answer: 8
How many faces does a triangular prism have?
- A triangular prism has 5 faces, 9 edges and 6 vertices.
- Count the faces: a triangular prism has 5 faces.
Answer: 5
How many vertices does a triangular prism have?
- A triangular prism has 5 faces, 9 edges and 6 vertices.
- Count the vertices: a triangular prism has 6 vertices.
Answer: 6