I' am new to inkscape and have problems to get all my path operations working. Several other problems could be solved with google, but now this one seems to be a bit tricky:
As you can see in the picture below the inner and outer circle are joined in a single path . This was made with two single circles and the Path --> Difference operation. The triangle down in the picture is also part of the path. The same should be done with the upper triangle. Unfortunately I dont' know I did this...

Ok so I want to cut/intersect path number one with the upper triangle. The yellow marked nodes should now be joined with path number one so that I can remove the path between node 10 and 20.
At the moment the upper triangle sticks/is snapped to the path 1 but I cannot remove the path between 10 and 20. It seems like the two nodes only lay above each other...
Thanks for your help!
