> No time for think of that, but I suppose it's a classic construction :)
> How draw the red curve "Developping of circle"

Hi Pilou - many of these types of mathematical curves are not really suited for "drawing" with the mouse exactly. This is the type of thing that you would probably need to generate using a more specialized program, maybe something like Mathematica.

It would be possible to construct this in MoI by using some fairly complex scripts to generate a point list and create a curve using those points. But that will be pretty involved.

- Michael