3D.jpgFlat shapes such as squares and octagons have two dimensions and can be easily drawn on paper.

Solids objects such as cubes and prisms occur in three dimensions and are difficult to draw on paper.

Three examples of such solids are shown below.

cuboid
triangular prism
square-based pyramid
Y9_Three_Dimensions_01.gif
Y9_Three_Dimensions_02.gif
Y9_Three_Dimensions_03.gif

Solids such as these can be described by the number of faces, edges and vertices they have.

face is a flat surface
An edge is where two faces meet
vertex is a point or corner

12 edges
9 edges
8 edges
6 faces
5 faces
5 faces
8 vertices
6 vertices
5 vertices


 

Nets

A net is a pattern in two dimensions which, when cut out and folded, will make a solid figure.

 

 

Cuboid

 

Y9_Three_Dimensions_04.gif

Net of a cuboid

Y9_Three_Dimensions_05.gif

Pyramid

 

Y9_Three_Dimensions_06.gif

Net of a pyramid

Y9_Three_Dimensions_07.gif

  

Views of Solids

Solids can be viewed from top, front, back and sides.

For a triangular prism

View from top
View from front
View from back
View from side
Y9_Three_Dimensions_08.gif Y9_Three_Dimensions_09.gif

 

Isometric drawings

Isometric graph paper, which is made up of triangles, instead of the usual squares, can be used to draw views of three dimensional objects. All of the dots on isometric paper are the same distance apart.

e.g. An isometric drawing of the cuboid is shown below. Y9_Three_Dimensions_10.gif

 

Y9_Three_Dimensions_11.gif