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CBSE - VII
Introduction to Solid Shapes
Introduction to Solid Shapes
All two-dimensional figures have only length and breadth.
Lesson Demo
All two-dimensional figures have only length and breadth.
For example, paper has only length and breadth, and hence, it is classified as a plane or two-dimensional figure.
Three-dimensional solid shapes have length, breadth and height.
For example, a biscuit tin is in three-dimensional shape.
Faces:
The flat surfaces that form the skin of solids are called faces.
Edges:
The line segments that form the skeleton of solids are called edges.
Vertices:
The points where three edges meet are called vertices.
The table shows the number of the faces, edges and vertices of some shapes.
|
Face (F) |
Edge (E) |
Vertex (V) |
|
3 |
2 |
0 |
|
2 |
1 |
1 |
|
4 |
6 |
4 |
The net of a three-dimensional solid is a two-dimensional skeleton outline, which, when folded, results in the three-dimensional shape.
Net
solid
Solid shapes can be drawn on a flat surface, which is known as the two-dimensional representation of a three-dimensional solid.
Sketches of solids are of two types: oblique and isometric.
Oblique sketches are drawn on squared paper. They do not have exact dimensions, but still convey all the significant aspects of the appearance of a solid.
Isometric sketches are drawn on dotted or isometric sheets and have the exact measurements of solids.
