# Getting Started with GeoGebra

Sorry - this is not an InterActivity yet and shouldn't be here ... but it is coming.

 A little screencast to get you going ... Online tutorials: screencasts plus written directions
 Interactivity - Construct a parallelogram ABCD with vertices A, B and C    Directions for interactivity In the top right: Reset button to start over or Undo button to undo last step. First draw sides \overline{AB} and \overline{BC}    How? Select the line segment tool and click on A and then on B (they will glow). You will get a line segment a joining A and B. Click on B and then on C. You will get a line segment b joining B and C. Now pick any of the 3 ways below to draw a parallelogram. You will always get the point D(-3,4)! One way to draw the parallelogram (based on definition that opposite sides are parallel).   How? Select the parallel line tool and click on point A and then on line b. You will get a line c passing through A and parallel to b=\overline{BC} . Click on point C and then on line a. You will get a line d passing through C and parallel to a=\overline{AB} . Click on the intersection tool and then click on the intersection point of c and d. You will get the point D at (-3,4). Another way to draw the parallelogram (based on definition that opposite sides are the same length).   How?  *Select the compass tool and click on center point A and then on B and on C. You will get a circle c with center A and radius the length of b=\overline{BC} . Click on point C and then on A and on B You will get a circle d with center C and radius the length of a=\overline{AB} . Click on the intersection tool and then click on the intersection point of c and d. You will get the point D at (-3,4). A third way to draw the parallelogram (based on definition that the diagonals bisect each other).   How? (With the line segment tool still selected, draw the diagonal c=\overline{AC} . Select the midpoint tool and click on c. You will get the midpoint D of   b=\overline{AC} . Right-click on the label "D", select rename and type in E and click on OK. Click on the line tool and click on B and then on E to get the line d. Click on the circle-center-point tool and then click on E and then on B. You will get a circle e with center E and radius the length of a=\overline{EB} . (It will pass through B.) Click on the intersection tool and then click on the intersection point of line d and circle e. You will get the point D at (-3,4). This browser does not have a Java Plug-in. Get the latest Java Plug-in here. How to save interactivity To save and then use the saved file, you will need to download and install GeoGebra If there is a menubar, click on File -> Save. If there is no menubar, double-click anywhere in the interactivity. A separate GeoGebra window will open (with menubar).   Click on File -> Save.

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