Migration from X: "Migration in this context means that you used X/Twitter until a point in time and then immediately shifted to using Mastodon."
I had a trial phase where I kept my Twitter account for a while, before later deleting it. So while I would normally answer "yes", I did migrate from Twitter to Mastodon, because of the "immediately", I'll have to answer "no". Not sure why you stress the "immediately", I find that a bit weird.
So the upside-down L is a marker that marks something requiring correction.
The next line that @Yendolosch hasn't dealt with yet says "vor Abschluß der Verhandlung berichtigt" that is "corrected before the official procedure was completed".
Next line starts with a short word I can't decipher, then "der Standesbeamte", that is "the town-hall official responsible for the citizen register", and has a signature something"mburg"
An arc length is - well, a length. Incidently, so is a radius. A length would be measured im m or inches or miles or what have you.
An angle is not a length. It is measured in degrees or radians.
So to say "by definition, radians is an arc length" is just a bit imprecise. That "basically" has a reason.
It would be a different story if those textbook authors could somewhere find a circle with radius 1. Not 1 m or 1 inch or 1 mile, but just 1.
