



Will you be at the NCTM Annual Meeting in Indianapolis next
week? If so, come see us at the Saltire Software booth number
1242. Otherwise, you can see us on the web at www.mathillustrations.com. Tips
this month: how to create some simple 3D figures with Math
Illustrations and how to configure Math Illustrations to work best with
your Interactive Whiteboard.

Fake 3D  Cone
[Video]
Math Illustrations is a
2D program. However, you can use it to make pictures of 3D
figures. For example, to create the picture of the cone shown, do
the following:
 First draw an ellipse.
 Select the two foci and Construct / Midpoint.
 Select the ellipse and change its line style to Dotted.
 Draw an arc on the ellipse.
 Create two line segments from the ends of the arc which will represent the edges of the cone.
 Make those two line segments congruent.
 Join the center of the ellipse to the vertex of the "cone", and make the line style of this segment Dotted.
 Hide the unnecessary symbols.

 
Fake 3D  Cylinder
[Video]
To make a diagram of a cylinder, we need a second copy of the ellipse representing its base displaced somewhat. To do this:
 Create an initial ellipse.
 Select the ellipse and use Construct / Translation. To specify the translation, draw a vector approximately perpendicular to the axis of the ellipse.
 So
long as the ellipses are quite flat, the foci are very close to the
perimeter of the ellipse, hence a quick way of getting a cylinder
picture is to simply join the foci.
For
a picture of the slice of a cone (a "conical frustum"), instead of
using a translation, we would use a dilation of the original ellipse,
whose center would lie at the tip of the cone.
[ Video]

 
Interactive Whiteboard
If you are using Math Illustrations with an Interactive Whiteboard,
you should be aware of "Smartboard Mode". This lets you select
multiple entities without holding down the Shift Key. Set Smartboard Mode using Edit / Preferences / Selection






