More polylines

Experiment with the prompts after you select "arc" from the PLINE prompt:

Command: pl PLINE From point: Current line-width is 0.0000 Arc/Close/Halfwidth/Length/Undo/Width/: Arc/Close/Halfwidth/Length/Undo/Width/: a

Angle/CEnter/CLose/Direction/Halfwidth/Line/Radius/Second pt/Undo/Width/ : a

Included angle: 90

Center/Radius/:.......

CE specifies the center (and therefore direction), D specifies the direction, A specifies the angle, and then the mouse determines the direction, S specifies the second point on the arc, which, after the third is picked, gives the direction too.