|Given two points above the
x-axis, there is a unique semicircle through those points with its
diameter on the x-axis. We'll create a tool that constructs that
To the right we place points A and B, then use the Perpendicular Bisector tool to construct the perpendicular bisector between them. We use the Intersect Objects tool to construct C, the point where the perpendicular bisector meets the x-axis.
Next, construct a circle with center at C that passes through A.
|We can use the Intersect Tool again to find
the two points D and E where the circle meets the x-axis. We hide
the circle, then use the Circumcircular Arc tool through points D, A,
E to construct a semicircle on the x-axis which we name semi .
So, we start with points A and B, and we end with the semicircle semi. Now we'll create a tool that does this immediately.
|From the menu select Tools > Create New Tool...
In the Output Objects tab, select the semicicle semi.
In the Input Objects tab, select points A and B (use shift-click or ctrl-click to select both).
|In the Name & Icon tab, type a name
for your new tool; I used SemicircleOnXAxis
. You can't use spaces, and you can also use this name as a
command in the Input Bar.
If you have a picture you'd like to use, you can select it by clicking the Icon... button. Click finish!
|Now you can use the new
tool. Create two points, click on the tool, then select those two
points - instant semicircle!
Now let's save the tool so we can use it in other constructions.
|In the menu select Tools > Manage Tools...
Select SemicircleOnXAxis then click Save As... You'll be asked to save a file with .ggt extension. Save your file as SemicircleOnXAxis.ggt .
After creating a new user defined tool you can save your settings using menu Options > Save Settings. From now on, your customized tool will be part of the GeoGebra Toolbar.
Or, after saving your custom tool on your computer (as a ggt file), you can import it into a new GeoGebra window by selecting File > Open and opening the file of your custom tool. Opening a GeoGebra tool file (ggt) in GeoGebra doesn’t affect your current construction. It only makes this tool part of the current GeoGebra Toolbar.