[Inkscape-user] Trim/extend feature questions

Hi!

I would like to achieve a trim/extent feature like in many CAD-like application can be found.

Here is a little screenshot what I trying to do: http://khiraly.googlepages.com/trim_extend.png

Here are the steps what I did: There are two lines and a circle, so 1. I converted the circle to path 2. I opened up the circle 3. I duplicated the line, and go to the Path->Cut Path menuitem 4. I repeated the above step to the other line

Sadly this precedure involves some imprecisement, I zoomed into, and created this screenshot: http://khiraly.googlepages.com/circle-imprecise.png

Can somebody propose a precodure where the result is mathematically correct, and does not have imprecisement? Needless to say, that I cant union the three paths together...

Or should I wait until a trim/extend tool arrives? (I use rev 20844, from today)

Any ideas?

Best regards, Khiraly