The path line exceeds of what its size supposed to be, I had tried everything but none seem to work.

Image:

You need to convert the black line with Stroke to path - add a new node at the middle of the top segment - select left+right node - drag vertically till it snaps:

what about rectangles?

Same procedure:

If you have a bunch of strokes to arrange you could do Stroke to Path -Path->union and Path->Intersection with a duplicate of the blade: