GeoGebra

What is it?

GeoGebra is a mathematics software that connects geometry, algebra, spreadsheets and graphing. For today, we will play with basic shapes and other geometric tools (lines, bisectors, angles), though the software also has the capability to create more complex 3D shapes/planes/functions.

Requirements

Today, we will be using the web-based GeoGebra tool, so only a browser is needed. However there is also a GeoGebra app available for download.

Where to start?

Go to http://www.geogebra.org, and click on GeoGebra Geometry. Be sure to keep this window open in a tab for easy reference!

When you open a Geometry window, you will have access to the basic tools:

From left to right, these tools are:

• Move (use this to move something you have already constructed)
• Draw a Point
• Construct a Line Segment
• Construct a Line
• Construct a Polygon
• Construct a Circle with Centre Through Point

1) Click on any of these tools, and, using the HELP notes (see below) where necessary, try it out.

Below the initial tool bar, click MORE to access more tools.

1) Create a triangle, using the Construct a Polygon tool.

2) Create a regular triangle, using the Construct a Regular Polygon tool.

3) Grab and drag the vertices of each triangle to see how the different shapes change.

HINT: Use the Move tool to select and drag the vertices.

Explore some of the other tools by doing the following:

1) Create a line segment.

2) Create a perpendicular bisector to your line segment.

3) Grab and drag one of the ends of the line segment to see what happens.

4) Create a triangle. For your vertices, use the two end points of the line segment, and then a third point somewhere on the perpendicular bisector.

5) Measure each of the three angles by using the angle measurement tool.

6) Select the Move tool, and click on the vertex of the triangle that is on the perpendicular bisector. Move the point along the bisector… what do you notice about the angles?

Want more?

Try out some of the other tools before moving on to the reflection piece below!