program DoHoa;

uses graph;

procedure KhoiDong;

var

 grDriver: Integer;

 grMode: Integer;

 ErrCode: Integer;

begin

 grDriver := Detect;

 InitGraph(grDriver, grMode,' ');

 ErrCode := GraphResult;

 if ErrCode <> grOk then

 begin  { Do graphics }

   Writeln('Graphics error:', GraphErrorMsg(ErrCode));

   halt(1);

 end;

end;

{-----------------------------}

{      CHUONG TRINH CHINH     }

{-----------------------------}

const a = 300;

var

  x0,y0,R,x1,y1,x2,y2,x3,y3: integer;

BEGIN

  KhoiDong;

  x0:= GetMaxX div 2;

  y0:= GetMaxY div 2;

  R := round((a/Cos(30*Pi/180)/2));

  setcolor(yellow);

  Circle(x0,y0,R);

  x1 := x0;

  y1 := y0 - R;

  x2 := x0 - a div 2;

  y2 := y0 + R div 2;

  Line(x1,y1,x2,y2);

  x3 := x0 + a div 2;

  y3 := y0 + R div 2;

  Line(x1,y1,x3,y3);

  Line(x2,y2,x3,y3);

  readln;

  closegraph;

END.