C.a.R.

This assignment is more difficult. The aim is to inscribe a circle in the given triangle, as follows:

First, make a macro to construct angle bisectors of arbitrary angles
Apply this macro to get the center of the inscribed circle.
Finally, construct the circle itself.

Here are the steps in the construction:

Select the macro generation tool . Notice the icon changes to , indicating that you are to provide the inputs for your macro. Below the construction window, you are prompted "Macro Parameters: Parameter objects?"
As parameters, select C, A and then B. Click the macro icon once more. The icon changes to , indicating that you should provide the targets (i.e. outputs) for your macro.
As a target, select the angle bisector (green ray). Click the macro icon once more. The "Define Macro" dialog box will appear.
In the dialog, name the macro "angle bisector" . In the "Macro Comment" box type in "calculates angle bisector from three points on an angle". Make sure "Hide construction" and "Hide Duplicates" are both checked.
In the first three "Parameter Prompt(s)" boxes type: "Point on one of the angle", "Angle vertex", "Point on other side of the angle". (This step is optional: these prompts will display when the macro is run).
Click "OK" at the bottom of the "Define Macro" dialog box to close it.
Next, right click in the construction window and select the macro you just created. Create an angle bisector for angle <ABC by selecting first point A, then B, then C.
As in the previous step, create the third angle bisector for the triangle. The three angle bisectors should intersect at a single point, which is -- the incenter!
Use the Perpendicular line tool and create a perpendicular line to line AC going through the incenter.
Select the Circle tool . With the intersection of the angle bisector lines as center, create a circle that contains the intersection of the perpendicular line and line AC. Notice that the circle is indeed inscribed in the triangle!

Solution