Assignment Four:

Basic Geometry

We have learned that the terms, point, line, and plane, are the undefined terms of Geometry, and that all of the other shapes and figures can be defined in terms of them. We are able to draw them and write the symbol for them. We have also learned how to draw and write the symbols for: segments, rays, and angles. Also, we are able to find the measure of an angle using a protractor.

Up until now, we have done all of this by hand. This means that our pictures look good, but not great. We are also limited to working with what we have drawn. It is impossible for us to stretch or move our diagrams around using old time pencil and paper diagrams. So, it would be nice to have diagrams that look better than anything that we could produce with pencil and paper and that are easier to manipulate. For this, there is a great program, Geometer's Sketchpad.

The purpose of this assignment is to learn how to produce the pictures and symbols using this program that until known we have drawn using old-fashioned pencil and paper constructions.

The Geometer's Sketchpad

Geometer's Sketchpad consists of two parts. The toolbar which is used to make the different figures and that looks like:

and the Sketchpad itself where the figures are drawn and looks like


The toolbar has six different tools. Of these six, we will only use the first five. So, we will not discuss the last box which has the arrow and three dots. The first box that we are concerned with is the top box which in the first picture is highlighted and contains the arrow.

This allows us to highlight and move objects on the sketchpad. Basically, it means that our mouse works like we are used to a mouse working.

The second box withe the single dot on it allows us to put points on the sketchpad. Click on this will allow us to put a point on the sketchpad whenever we push the right button on the mouse. A picture of this can be seen next.

Notice that the point box has been highlighted and that there are now points on the sketch pad.

The third button is used to make circles. So, we first highlight it then move our mouse onto the sketchpad. Now, it works like making a point. We right click and hold down our mouse button. This allos us to expand the circle to the size that we want by moving our mouse. To stop changing the size of the circle, simply let off of the mouse button. A picture of a circle is below.

The fourth button currently looks like a segment. This button allows us to make segments lines and rays. Notice that this button has an arrow in the lower right hand corner. This means that this tool can do more than one thing. To find out all that it will do, simply click and hold on the box. When this is done, the toolbar should show a picture of a sement a line and a ray. Now, select the one that you would like to make by moving the cursor onto the desired picture. One can now make any of the following three figures.

The top figure is a segment because it has two endpoints. The second figure is a ray because there is one endpoint and it continues forever to the right. The bottom figure is a line. It has no endpoints and continues in both directions forever.

The final tool that we are interested in using is the fifth box that has a capital A on it. This box allows us to name our figures. When we click on this box, our cursor will change from an arrow to a hand. Now simply move the hand to a point or a figure that you would like to name and when the hand turns black right click your mouse. This will then give the figure a letter name assigned by the computer. If you would like a different name simply double click the mouse and a new box will pop up with the current name of the figure in it. Next, type the new name and hit enter and the new name will appear. Examples of this can be seen below.

This should be enough information to get you started using Geometer's Sketchpad. Now, click on the links below for your assignments.

Homework Assignment Four

Bonus Assignment Four

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