STEP 2: MIRRORING (with 2 methods)
1 A. By entering data:
MIRROR: select rim <enter>
to 1st point enter "@(radius)<180"
to 2nd point enter "@(radius)<270"; delete old...: "N"
2 B. By clicking on drawing:
1st point: select midline on 1
2nd point: select 1 again; delete old...: "N"
2. Complete upper left line (use F8 then grips to join to rim and midline)
Show the grips by clicking on the objects; join the lines by dragging and overlapping their grips (you can drag a grip when it turns red under the crosshairs)
Continue to step 3