1000 degree bend?

[changrilla]

Hi, I hope someone can help. I've never been able to work out the angle when making a bend in the middle of an object. This http://www.mgcsoft.com/junk/1000_degree_bend.jpg is the sort of thing I'm talking about. It was a 100u length 3u dia cylinder which I've bent using bend clamped to 90° as well as I can by eye which turns out to be 1000° in the interface. Where does the 1000° come from. The centre section is pi*d/2 long which gives me a 3u radius as intended. I generally get round this by making just the elbow and extruding the ends but I'd like to know what the relationship between the intended angle and the interface readout is.

tia

Gordon