How to use path operations to make a ribbon?

Question

First, I draw a closed path like this:

Then, I draw a line down perpendicularly down from one side of the path (I have snapping turned on, so that I can snap to the path):

I copy and paste this line to the other end of the path:

Then, I copy the initial closed path, and place it below the original like so:

Altogether, these are 4 paths involved: the two lines, and the two loops.

I would like to produce something that looks like this:

Where the paths involved are (forgive my shaky hands):

There are two closed paths: the top one (in red) and the bottom one (in blue).

How can I get something like that from the 4 path intermediate step? I suspect it is a matter of the applying the right boolean path operations? Or, is there an easier way to do this from the very first step?

Answer 1

Maybe this might not be the way to draw in a vector graphic program, but it can be done in a few steps:

1. duplicate the lower polygon. The additional shape in shown in red

2. select one copy of the lower polygon and the upper polygon and create the division between both shapes:

3. Now select the other copy of the lower polygon. The part within the ribbon can now be deleted. To do this use the node tool to break the path somewhere in the to be deleted part

4. delete all nodes within the shape

5. finished ribbon:

Answer 2

That's not the way to draw in a vector program. This is not Inskape but sure it has similar features to make the same shapes using a half of an ellipse, duplicating it and joining its extreme points.