I need help iam using a joystick and i need to change lateral and forward paratemer according to the angle i got on a joystick

[SteveJG]

Your Canvas1 only provides positive x,y values. There is no negative axis. See http://www.appinventor.org/bookChapters/chapter17.pdf the section The Canvas Coordinate System.

You seem to expect coordinate system similar to this using the Canvas but the Canvas only provides positive values:
+100
|
|
-180--------------0--------------------+180
|
|
-100

Sorry, that didn't post very well.

Arc drawing example DrawArc Example

@EW_P

A simple example will do so any arc will be drawn.

Perhaps you could draw a diagram showing how this would work. Post the image If you do that someone could possibly advise on how you could do the required coordinate transformation mathematics?