> In this case (show points enable) does exist a trick for move the last point as a "tangente" ?

One easy way is to just draw a line like you mention.

Another way is to select your point, then use the Transform / Move tool. Then drag a construction line along the tangent direction that you want.

The Transform/Move command can sometimes be a better way to move things with precision, since the existing object remains snappable, and you can also create construction lines with it easier than you can with dragging style movement.

- Michael