Initialy, i found this idea from Michaël LAUNAY on Youtube ([i]https://www.geogebra.org/m/MXbWpzS6[/i]).[br]Freely inspired from [b]Steve PHELPS[/b] ([i]https://www.geogebra.org/m/dqKkQEv7[/i]) and [b]Johan MATHIEU[/b] ([i]https://www.geogebra.org/m/MXbWpzS6[/i]), and some others also, right here.[br]Thanks to all of them for this beauty !