2. 1D, 2D and 3D
objects
Length, Breadth and Height are dimensions. For example, a line has one
dimension (length), a square has two dimensions (length and breadth), and a
cube has three dimensions (length, breadth and height).
Therefore,
1D = 1 Dimension (line)
2D = 2 Dimensions (square)
3D = 3 Dimensions (cube)
3. Some examples of 3D
objects
Pyramids of Egypt (Pyramid) Rubik's Cube (Cube) Basket Ball (Sphere)
4. Euler’s Formula
‘Leonhard Euler’ was a pioneering Swiss mathematician and physicist. He made
important discoveries in fields as diverse as infinitesimal calculus and graph
theory. He had invented a formula (popularly known as the Euler's formula):-
V - E + F = 2
Where,
V = number of vertices, E = number of edges & F = number of faces
5. For Example,
1. Tetrahedron :- V = 4, E = 6, F = 4 &
Therefore, 4 - 6 + 4 = 2
2. Cube :- V = 8, E = 12, F = 6 &
Therefore, 8 - 12 + 6 = 2
6. Polyhedrons
A Polyhedron is simply a three-dimensional solid which consists of a collection of
polygons, usually joined at their edges.
7. Net of a
3D
Object
The figure drawn on a 2D
paper which when folded
forms the 3D object is
called as the net of a 3D
shape.
For
Example,
8. Prisms and Pyramids
• A prism is a polyhedron, with two parallel faces called bases. The other faces are
always parallelograms. The prism is named by the shape of its base.
• A pyramid is a polyhedron formed by connecting a polygonal base and a point,
called the apex. It is a conic solid with polygonal base
