I want to know the orientation (relative to North) of a bay. The idea is, if I draw a line along a coast, and it crosses the bay mouth, I want the direction of the line perpendicular to that line (as shown in the pic). I want the orientation of the black line.
I'm thinking there must be a simple way to do this, but I'm not able to figure it out. I've used the "New Shape File" and "Add line Feature" (to make the green line), but I don't know how to make a line perpendicular to it, or how to read the orientation (I drew the black line in GIMP). I'm a total beginner in QGIS.
I am working with QGIS 3.16.10-Hannover version.