搞定:
procedure TForm1.BitBtn2Click(Sender: TObject);
var
i:integer;
x,y,anl:double;
begin
series1.XValues.Order:=loNone;
for i:= 0 to 180 do
begin
anl:=i*3.1415926/180;
x:=10+10*cos(anl);
y:=10+10*sin(anl);
series1.AddXY(x,y,'',clred);
end;
for i:= 180 to 360 do
begin
anl:=i*3.1415926/180;
x:=10+10*cos(anl);
y:=10+10*sin(anl);
series1.AddXY(x,y,'',clred);
end;
end;