My understanding of Shapr’s sketch tool was that any intersections between sketch lines would create separate segments.
I tried to create a half circle, but found that my circle line wasn’t its own segment.
How can I create a selectable half circle? (Just using a basic shape as an example, I’m really curious how I should be thinking about creating/selecting segments created by intersecting lines)
See this video below:
Use the Trim command to remove the other half.
Thanks @McD!
Are there any options that don’t involve deleting other parts of my geometry / sketch?
Thinking ahead to cases where I am drawing more complex sketches.
I typically duplicate a sketch if I want elements out of it. In your case, I might redraw the circle afterward. But then you’ll have a duplicate line where the original half circle remained.
Ah, makes sense! Thank you 
Another noob question I haven’t posted yet - how do you duplicate a sketch? I’ve been working around not knowing how to duplicate any part of a sketch by always projecting the parts I want onto another plane. Sometimes I just want to highlight the parts I need and create a copy but moved elsewhere
Ah just noticed the little [+] on the sketch when in ‘move’! Not sure how to just entirely duplicate a sketch for later use though while keeping it in the same position.
DON, this one is easy. Using the pencil, tap and hold for a second or so until you see the little circle form and then drag and select your sketch. Then tap on the little + and then move your sketch to the side. Remember to untapped the + otherwise you’ll keep duplicating it. Give that a try, and let me know if you need further help.
Another way, is to select your sketch and then add a plane to it, offset in a little bit. And then project your current sketch onto that plane. You can then hide the original plane and work on your new sketch.