Shapes and Figures.... Both 2D and 3D

In this week’s post I am going to be talking about shapes and figures and what it takes to be considered a shape or figure.

                Do you know the difference between a polygon and a polyhedron? To be perfectly honest it is fairly simple. The formal definitions of each term are as followed. A polygon is a plane figure with at least three straight sides and angles, and typically five or more. Here are some examples:

                                          

                                         

A polyhedron is a solid figure with many plane faces, typically more than six. Another way of explaining them would be that a polygon is flat plane or figure (it is 2- dimensional) and a polyhedron is figure with many planes (usually made up of many polygons and is a 3- dimensional).  Here are some examples of some polyhedrons:

                                                 

Within these figures there are many more shapes that are different from one another. Some examples are pyramids, prisms, cones and cylinders:

               

       Pyramid                      Prism                    Cone                 Cylinder

Now, we remember from last week’s post that “right” means creating a 90° angle. This applies with polyhedrons as well. If you have a right pyramid, cone or cylinder that means that a straight line from the apex or center of the figure down to the base creates a 90° angle and if you have a right prism then all faces have to be rectangles. The word “oblique” means it’s neither parallel nor at a right angle to an implied line, basically meaning slanted. If you have an oblique pyramid, cone or cylinder than a straight line from the apex or center of the figure is slanted creating an angle other than 90° and an oblique prism is when the faces are not perpendicular to the plane of the base.  All of the examples above are right polygons, now here are some examples of oblique polygons:

                                     

Oblique Hexagonal   Oblique Pentagonal        Oblique                       Oblique

       Pyramid                    Prism                       Cone                         Cylinder

The reason some of the figures above, such as the pyramid and the prism, have words like hexagonal and pentagonal in their name is because the bases are a specific shape. You can see that the base of the pyramid has six sides which makes it a hexagon so adding “hexagonal” to the name helps add more detail to understanding what the shape looks like.