@Kitonum 

This solved all my problems, thanks.

@Kitonum

This is just what I was expecting, a working example.

I´ve seen that the proc's are very useful but I'm new with Maple.

I only have another question. what if I want a 3d plot? there is an error for the animate had more than two components, is there another command or I'm using it wrong, just added [x, y(x), x] to the proc.

Thanks a lot.