Hi Alan,

>>
Assuming I understood your requirements correctly, the code below should do it. It returns a negative distance from centre for angles greater than 180 which from one viewpoint is correct.
Is this what you wanted?
>>

Thanks but, sorry, I should have described the problem better... the axis of the rectangle needs to be the same as those of the circle (i.e orientated vertically/horizontally). Also both the start and end angles for the arc can be non-zero. See my message to Gregory for a bit more detail.

Regards,
Viv