# Basic Geometric Constructs: Compass and Straightedge with GeoGebra

*** To use this offline today, you need to get the pre-release of GeoGebra 3.1:  Click here ***

What is a pencil, a compass. and a straightedge in GeoGebra?

Here is a little mathcast (video) explaining the tools we will use ...

What do we do when it says: Given ...?

Here is a little mathcast (video) explaining how to get the "givens" ...

1. Given a point A ...

2. Given a line m and a point A on m ...

3. Given a line m ...

4. Given an angle α ...

5. Given a circle c ...

How do we do and undo? (a few more techniques)

Here is a little mathcast (video) explaining a few more useful techniques ...

1. Using the Intersection Point Tool

2. Using the Compass Tool    - the tool that does:

"I need a circle with center A and with a radius the distance between B and C."

"a.k.a. Take your compass and stick the needle in point B and widen it until it reaches point C.
Now stick the needle in point A and draw a circle."

3. Undo/Redo /
4. Forget the order in which you constructed? Look at the Construction Protocol.