Move B on the
circle! What is the track of the midpoint M between A and B?
Select
the track tool. Then click on M, because we want the
track of this point. Then move B with a left mouse button drag.
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The automatic track tool does the same automatically. Select
it, then click on M, then on B. B is bound on the circle, so it will
automatically move on it.
You can stop the animation of the track with a left mouse
button click.
Continue
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