Page 1 - LN3-Polyhedron

SAI International School
CLASS - VIII

Mathematics
CHAPTER-10: Visualising Solid shapes Lesson Notes-3

SUBTOPICS: Faces, Edges and Vertices, Polyhedron, Euler’s
Formula

Faces – All the flat surfaces of the three 3-D shapes are the faces. Solid shapes are made up
of these plane figures called faces.
Edges – The line segments which make the structure of the solid shapes are called edges.
The two faces meet at the edges of the 3D shapes.
Vertex – The corner of the solid shapes is called vertex. The two edges meet at the vertex.
The plural of the vertex is vertices.

Polyhedrons

Polygons are the flat surface made up of line segments. The 3-D shapes made up of
polygons are called polyhedron.

 These solid shapes have faces, edges and vertices.
 The polygons are the faces of the solid shape.

 Three or more edges meet at a point to form a vertex. The plural of word polyhedron is
polyhedral.

 Non-polyhedron: The solid shape who’s all the faces are not polygon are called non-
polyhedron. i.e. it has one of the curved faces.

1