Now let's first change the color of semicircles to make it look like protractor. Then, we will need another semicircle arc to move the angle guess arrow. This arrow should move from )0[math]^\circ[/math] to 180[math]^\circ[/math]. [br][br]To create the semicirle arc, you may use [icon]/images/ggb/toolbar/mode_semicircle.png[/icon] or [icon]/images/ggb/toolbar/mode_circlearc3.png[/icon], or use SemiCircle or CircularArc command.

Now, you create the semicircle.