请调整此部分：
- ...
- ;if not - line angle in other direction
- ) ;_ end of if
- [color=magenta] (setvar "osmode" 0)
- (setq PL (* SC 0.20)
- PW (* SC 0.08)) ;set arrowhead width
- (setq PT1 (polar EPT ANG1 (/ (- (distance EPT1 EPT2) PL) 2.0)))
- (setq PT2 (polar PT1 ANG1 PL))
- ;set arrowhead length, based on current dimscale
- (setvar "osmode" 0)
- (command "PLINE" PT1 "W" "0" PW PT2 "") ;draw arrowhead
- [/color] (setvar "OSMODE" XOSMODE)
- ...
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