INRODUCTION

THREE-DEMENSIONAL FIGURES


 Three dimensional figure is a solid figure having three measures.Some examples are pyramids, cylinders, prisms, cubes and cuboids.





- Apart from three dimensional figures, there are also one and two dimensional figures.


Examples


1. A line is one – dimensional. There is one direction to move along it. (up or down it).


2. A flat shape is two- dimensional. There are two directions to move across it (up or down, and left or right).


The diagram below show objects which are one or two –dimensional.





-The –dimensional space contains line and planes. Consider a diagram of a cube:



Note:


When we refer to a cube or cuboid ABCDEFGH, then ABCD and EFGH are apposite faces, with, E opposite A, F opposite B and so on , as in the diagram above


- Line and planes can be parallel or perpendicular. In the diagram above:


· The lines AD and EH are parallel.


· The lines AD and AE are perpendicular.


· The planes ABCD and EFGH are parallel


· The planes ABCD and AEHD are perpendicular


· The lines AD and CE are neither parallel nor perpendicular and the planes ABCD and EHCB are neither parallel nor perpendicular


EXERCISE 3.1A


The diagram show a cube ABCDEFGH. The face ABCD is horizontal. Give


a) (a) Another horizontal face


b) (b)A vertical face


c) (c)A horizontal line


d) (d)A vertical line





2. Refer to the diagram for question. Write down


a) Two faces which meet at GC


b) Three edge which meet at F