Faces, Edges And Vertices
Chapter Name : Visualizing Solid Shapes |
Sub Topic Code : 104_08_10_04_01 |
Topic Name : Faces, Edges And Vertices |
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Sub Topic Name : Faces, Edges And Vertices |
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Introduction
Some 3D shapes have faces, edges & vertices, The polygonal regions are called faces, which meet to form edges, which in turn meet to form vertices
Pre-Requisites:
3D shapes, Convex Polygon, Regular Polygon
Activity:
Look at an apartment complex near your house. Is it a polyhedron? What kind of a polyhedron? Count the no. of faces, edges & vertices that it has
Real Life Question:
Is a football a polyhedron?, Is the sweet box a convex or regular polyhedron?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Face | Polygonal plane surfaces |
| Edge | Edges are lines wherein Faces meet |
| Vertices | The points where lines meet |
| Polyhedrons | 3D objects which have faces, edges & vertices |
| Convex polyhedron | A polyhedron having convex polygons as bases |
| Regular polyhedron | A polyhedron having regular polygons as bases |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| A large steel glass | It looks like a cone, whose little portion from the top was cut. This is called a “truncated cone”. However, it has a curved surface which has no edges & vertices and hence, it is NOT a polyhedron |
Real life uses :
Study of the kind of polyhedron does not have really major applications. But, it is used to differentiate among the 3D objects in general so as to be able to design the machinery parts in general
Places to visit :
Commercial Building, Shopping Mall
Practical examples around us
| Examples | Explainations |
|---|---|
| Ice cream Cone | Invert it & you will notice it is a 3D figure (cone). Is it polyhedral? No! Bcoz it does not have edges & vertices. |
What you learn in Theory:
3D objects with curved surfaces are NOT polyhedrons, Prism is a polyhedron whose base & top are congruent polygons & lateral faces are parallelogram in shape, Pyramid is a polyhedron whose base is a polygon & lateral faces are triangles
What you learn in Practice:
All the 3D objects around us are either polyhedrons or NON-polyhedrons