Math 5335 Fall 2009: Installing and using GeoGebra1. Installing GeoGebra2. Getting Started3. The Finer PointsLabel, Names and AppearancesGrid and AxesShortcutsPrintingScreenshotsMath 5335 Fall 2009: Installing and using GeoGebraThis semester you will have a number of “lab assignments” which require you to use GeoGebra, a dynamicgeometry program. GeoGebra lets you explore geometric ideas and constructions on your computer. It’sfree and is written in Java, so it will run on any computer platform which runs Java applets. That includesWindows, Macintosh or Linux computers. You can also run it in a web browser in any computer lab oncampus.The instructions below show you how to install GeoGebra and use some of the tools you’ll need to completeyour homework assignments. The GeoGebra website has extensive documentation and is a good resourceif you need to look something up. You don’t have to turn anything in based on these instructions; yourhomework will be posted separately.1. Installing GeoGebraUse a web browser to go to http://www.geogebra.org. The recommended way to install GeoGebra onyour own computer is with Webstart. To do this, click the Webstart button on the homepage and on thenext page. This will download GeoGebra to your machine and place an icon on the desktop. If that fails,click Download on the home page and follow the directions on that page to get the correct package for yourcomputer.If you are using GeoGebra on a library computer you can also run it as a java applet by clicking Webstarton the homepage and then the Applet Start button.2. Getting StartedWhen you start GeoGebra, you will see the following window. (This screenshot is from the GeoGebraQuickstart guide, available at the homepage.)By selecting tools from the Toolbar, you can use your mouse to create things in the Drawing Pad.Equations and coordinates for all of your points, lines, circles, and so on will be displayed in the AlgebraWindow. You can also use the Input area at the bottom to create things with typed commands instead ofusing your mouse. Also note the important Undo and Redo buttons!To see how everything works, try the following steps.(1) Select the Point tool, which looks like a point labeled with the letter A. Click two different locationsin the Drawing Pad. GeoGebra will create two points labeled A and B in the Drawing Pad. Theircoordinates will also appear in the Algebra Window.(2) You can also create points with specific coordinates using the Input Field. Type C = (4, 1) inthe Input Field – use a capital C! – and you should see a third point appear in the Drawing Pad.If it doesn’t work, make sure you typed everything exactly as shown, including the round parentheses.(3) Now click the Polygon tool, which is the shaded triangle near the middle of the toolbar. In order,click on A, B, C and A. GeoGebra will create a polygon (in this case, a triangle) using those points1as the corners. Notice GeoGebra automatically creates and labels the edges of the triangle. In theAlgebra Window it lists the edges and shows you the side lengths. For example, in the trianglebelow, the side a which is opposite the point A is 3.06 units long.Also notice that GeoGebra has created an object called poly1. This is the triangle itself, and itsvalue in the Algebra Window is the polygon’s area – 4.33 in this case.(4) You can create polygons triangles and other shapes without creating the corners first. Still usingthe Polygon tool, click four different places in the Drawing Pad and then one more time at the firstpoint to finish your shape. GeoGebra will create another polygon named poly2 and show you itsarea and its side lengths in the Algebra Window. See below.(5) The Algebra Window shows “Free Objects” and “Dependent Objects.” The free objects are theones you created – the seven points in the Drawing Pad. The dependent objects are constructedautomatically. The power of GeoGebra is that you can change the free objects and the dependentobjects will change automatically. Try it! Choose the Move tool (the arrow / mouse cursor on theleft of the toolbar), click on point A, and drag it around.You can also click in the middle of a polygon and drag it around. GeoGebra automatically movesthe points and updates their coordinates in the Algebra Window.Finally, although you won’t often need to do this, you can move a point by redefining it in theInput Field. Type A = (0, 2) (or some other coordinates), hit return, and the point and the trianglewill be updated.You may have noticed that the toolbar icons have little arrows on them. If you click on the bottom ofthese icons you can choose from many more tools. Most of them are fairly self explanatory, and once you’ve2chosen a tool brief instructions for using it appear to the right of the toolbar. One of your first technologyproblems requires you to work with lines, rays, and intersections; to practice using those tools try thesefollowing steps.(1) Create a new, empty Drawing Pad by choosing File > New.(2) A ray has a starting point and continues forever in one direction. To create a ray, choose the Raythrough Two Points tool (which is in the drop down list below the picture of a line; click whereyou want it to begin, and then click again to show GeoGebra which direction the ray should extend.(3) In the same drop down menu, choose the Segment Between Two Points tool and click on twonew points in the Drawing Pad to create a line segment. Then use the Line Between Two Pointstool to create an infinite line through two more points. Try to make the line cross your segmentand your ray. If necessary, use the Move tool to move the points around until your picture lookssomething like this:(4) Under the Point tool, select the Intersect Two Objects tool. Click on your ray and then yourline. GeoGebra should create a point G which marks the intersection of the ray and line. G is adependent object – you can’t change it with the Move tool. But if you move the ray or line, G willautomatically change!(5) Below the Perpendicular Line tool (the fourth icon in the toolbar) is the Parallel Line tool.Select it, then click on A and your line through EF . GeoGebra will create a line through A whichis parallel to the line. Your Drawing Pad should resemble the following:3Use the Move tool to drag A around and see how the automatically constructed objects (like G orthe perpendicular and parallel lines) are updated.Later in the semester you will need to use some of the more