Drawing an arc dynamically

[realMakc]

flash's curveTo draws bezier arc. it looks like this:

so yes, if that's what you mean by arc, it will help. if you mean circle arc, you still could use multiple curveTo-s to draw it approximately. in either case, you will first have to decide how to deal with user input that does not resemble arc. commonly used method for this is least squares, but I bet the formula will turn out rather complex for the arc (edit: check this paper), so you should try something else.